Script Compilation: Switching from D&D to GURPS

Script Compilation: Switching from D&D to GURPS

I've been asked to post transcripts of my videos here for ease of reading, so let's do this. I've decided to post scripts in thematic batches, consolidating particular subjects into a single post. This post will have all transcripts related to switching from D&D to GURPS.

Why play D&D in GURPS?

If you’re new here – GURPS is a generic universal roleplaying system published by Steve Jackson Games. It has gotten something of a bad reputation that is mostly based on… basically just some silly memes. Of course, it is not a perfect system, but it is functional and not at all as complex as the memes would tell you.

I think a better title for this video would be "Why do I play D&D in GURPS?" If you are aware of my blog, you probably know that I'm mostly preoccupied with porting all kinds of D&D content to GURPS. Why do I do that instead of just playing D&D? And why do that when GURPS already has the Dungeon Fantasy line and even DFRPG? I'll try to divulge my thoughts on this matter.

When people think of D&D (keep in mind that I started with the third edition), they usually think of hack-and-slash dungeon crawling games. I don't think I've ever played a D&D game that was strictly dungeon crawling-focused. There was always a plot, social encounters, various NPCs to interact with, it wasn't always only about combat. However, all that noncombat stuff was poorly supported mechanically, but you could still roleplay it all. What I liked about D&D the most was a vast amount of lore and character options. When you read a D&D book, your mind always concocts various situations, encounters, plotlines, or ways to weave something into the world. Then you realize that it's all very gamified - as soon as you reach a certain level, hordes of orcs stop being a threat, taking on a dragon stops being an undertaking that requires careful planning and a lot of resources, various minor abilities become useless, and the world suddenly feels much less magical, evocative, and believable.

I remember the first time I read the D&D 5e Player's Handbook. My reaction was "Why did they do that? Why would I play this dross?" The absolute lack of options and customization took out half the fun for me. I still gave it a shot once just to see that maybe it plays better that it seems. And it kind of was even worse than I expected.

During my D&D "career", I've been browsing all kinds of roleplaying forums. Apparently, most of the games belonged to two types - core only (Why would one limit the options like that?) and anything goes. The latter meant that anything published by WotC was fair play, but, of course, the DM had to veto absurd stuff. Nevertheless, there were many people who would create absolutely broken characters as thought experiments, but some would even try to play them and hope that the DM does not notice that and let them "win" the game. (And such people exist in the GURPS community too.) This entire mindset of "you have to know the system well to be able to notice exploits that the players can come up with from a mile away" created something of a mistrust of all things unofficial. Homebrew and third-party material was frowned upon, even though official material sometimes had much more broken stuff. But at least it was familiar. People just did not know how new things would interact with the old things and couldn't be bothered to learn, so the immediate reaction to homebrew material usually was negative.

When I was starting out with GURPS, I was positively surprised by the number of options. I would, for example, read GURPS Psionic Powers and understand how psionics works in GURPS. I would read GURPS Magic and understand how magic works in GURPS. Only when I read through GURPS Powers and GURPS Thaumatology I understood the most important thing about the system, and the system itself just clicked in my mind - everything works the way you want it to work. This is why the frequent questions I see online, such as "How does magic work in GURPS? How does psionics work in GURPS? How do spirits work in GURPS? How do dragons work in GURPS?" just make no sense to me - everything works the way you want it to work. Isn't that great?

Remember how you might've wanted to change something about D&D, but couldn't? Now you can create your perfect system, the one that meets all your expectations, the one that allows a world to make sense to you. Basically, no GURPS game is the same, because every GM does things differently, you're not supposed to strictly follow a certain template that some people expect to see in the GURPS books. GURPS is a toolkit that lets you create your own system for your own needs. GURPS Dungeon Fantasy is not my thing not only because of the templates, basic Magic, but also because of its strict dungeoneering focus. If that's your thing - go ahead and enjoy some DF! If you grew up reading Forgotten Realms novels, but the actual system prevented you from imitating these stories due to its mechanics, now you can! Weren't content with the subpar support for non-combat activities? Now you can have anything you want. Overall, it all depends on what you like or do not like, and what kind of game you are looking for.

So, basically, GURPS is the perfect D&D for me. I created a setting where I managed to incorporate all the various lore that I've read in the D&D books. But not only D&D 3.5, but I can take content from AD&D, D&D 4e, 5e, Pathfinder, and literally anything else and port it over to GURPS, and it will make sense and seem natural. I've had gigabytes of third-party supplements for D&D that I've never had a chance to use because some of the very cool ideas were implemented abysmally - but now I can! Sure, it turned my setting into a "kitchen sink," but that was the intention. I know that nowadays kitchen sinks are stigmatized, because the modern trend is a "no, you must have no more than four races in your game! and no elves, they are too cliché and overused", but I find the diversity of options to be very believable - just look at the real world!

However, all the aforementioned means that it's more difficult for a GURPS GM to find players, because not everyone will share his vision. Also, creating the game framework that satisfies you will take a lot of work – you cannot just wave a magic wand and get your perfect game. But if you put some effort into this undertaking, I’m sure it will be worth it. And, honestly, I find all the work I do very fun by itself.

What is the difference between D&D and GURPS?

First of all, I’m going to talk from the position of D&D 3.5, but as far as I recall, 5e works similarly in some ways. I guess this is as good of a place as any to mention that GURPS does not really have the so-called edition wars. Every edition of GURPS is a refinement of its predecessor, and there is no reason to, for example, start with the third edition. If you’ve played it for your entire life, then sure – keep playing. Practically everything in terms of mechanics was officially updated from the third edition to the fourth edition, which is the most current one, and there is no plan at all for the fifth edition to happen, as least in the foreseeable future. There are some books there were not updated, but most of them are setting books, and those can be used in any edition and do not really need an update.

The next meta thing before I get to the mechanics is the lack of an SRD. D&D and Pathfinder have online system reference documents that make the games more accessible and, technically, free – only to some degree for D&D, and completely free for Pathfinder. GURPS has nothing of this sort, you will have to get the books, but you won’t need that many of them. And there is GURPS Lite that is something of a free introduction to GURPS, but I would advise against using it. In my opinion, it fails to properly show off what GURPS is. If GURPS Lite was my introduction to GURPS, I would never have gotten interested in this system.

At the start of the character generation section of the Player’s Handbook we have abilities. D&D has six abilities – Strength, Dexterity, Constitution, Intelligence, Wisdom, and Charisma. GURPS only has four primary attributes – Strength, Dexterity, Intelligence, and Health. While in D&D hit points are based on class hit die, level, and Constitution, in GURPS hit points are based on Strength. It used to be Health-based in the third edition though. GURPS also has secondary characteristics, such as Will, Perception, Hit Points, Fatigue Points, Basic Speed, and Basic Move. Will and Perception are based on Intelligence by default, but decoupling them from it is a very common houserule. You might have noticed that GURPS does not have the Charisma attribute. In D&D, Charisma is something of a combination of physical appearance and sociability, but in GURPS, reaction modifiers are much more specific. You can set your Appearance, have good social skills, Reputation, Social Regard – there are many traits that affect how others react to you, including the one called Charisma. The bonuses and penalties, of course, are applied in different situations, and this allows you to make many so-called “face” characters that are very distinct from each other – not just pump up your Charisma stat as high as possible and buy appropriate skills.

The next section is race. Races in GURPS are just packages of traits, be they attributes, advantages, or disadvantages. Depending on the game, they might be inaccessible otherwise. Also, unlike in D&D, where all races are made equal if we disregard Level Adjustment from D&D 3.5, each race costs a set number of points that depends on what the race actually gives you. The baseline is human that does not cost anything.

Next up are classes and levels, both of which simply do not exist in GURPS. GURPS is a point buy system, where you construct your character out of traits, positive or negative, that cost points. However, you may be limited to an occupational template, if, for example, you’re playing GURPS Dungeon Fantasy. But that exists specifically to emulate the D&D experience. I don’t like templates. Nonetheless, while you can discard class as a mechanical concept, you can keep it as a concept. If you want to make a sorcerer, you are free to do it in any way you want, without the constraints imposed by the predetermined set of class features. So, instead of being a level 5 Sorcerer, in GURPS you are a 200-point character that can cast spells. Obviously, this allows for infinite customization, but may lead to a choice paralysis. Also, since there’s so much you can do, you can easily create a broken character – this is something GURPS haters like to talk about. But why would you create a broken character? I think this is a mindset problem. I don’t want to sound stuck up, but you have to adopt a more mature mindset that if you want to play a good game (or play at all), you have to make a character that will be fun to play, a real character, and not a broken build from an optimization subforum. By default, GURPS is not balanced and it cannot be balanced, but it’s the job of the GM and the players to make it balanced.

The next chapter is skills. While in D&D, skills are something of a secondary thing, in GURPS they play a very important role. In GURPS, skills represent what your character can do – from speed-reading to sword-swinging to meditating. Skills have levels that are tied to their controlling attributes that vary from skill to skill and sometimes from application to application. But if you do not know a certain skill, it does not mean that you can never use it! There is a system of defaults that lets you use a skill at a default, basing it on another skill or an attribute with a penalty. So, if you do not have the Two-Handed Sword skill, you can still swing one using Dexterity – 4. GURPS encourages breadth, not depth when it comes to skills.

You might say that feats do not exist in GURPS, but they can be represented by certain advantages, skills, or techniques. Just look at the power-ups from GURPS Dungeon Fantasy! They are advantage packages that basically are feats.

Alignment, a very contentious topic in D&D, does not exist in GURPS. But you can make it exist, if you want! But that’s a topic for another video.

Magic and spellcasting, if you watched my previous video, work the way you want them to work. GURPS has a variety of premade magic systems for you to choose, and even has supplements that not only allow, but encourage you to design your own magic system. I find that Sorcery and other variants of Magic-as-Powers works the best for D&D-style games, but again, this is a topic for another video.

And the only thing that is left is combat. Basic attack bonus, full attack – forget it. In my opinion, GURPS probably has the best combat system out of all tabletop RPGs. It can be made as complex as you want, but even in its most basic form presented in GURPS Basic Set: Characters it is much more detailed and fun that what it is in D&D. I strongly suggest using the expanded combat system from GURPS Basic Set: Campaigns and GURPS Martial Arts, unless you hate fun, of course. While in D&D, you are limited to just an attack and a set of combat maneuvers that are either underwhelming or even locked behind class features, like in 5e, a GURPS character can do anything – or at least attempt to do anything. A quick defensive sword thrust to the knee and an axe swing to the face will all work differently both for the attacker and the defender. Contrary to the popular belief, GURPS is not a reality simulator. However, everything is grounded in reality, so if one could attempt something in real life, one can do it in GURPS too. You don’t do an abstract attack and detract HP, you evaluate the enemy, make a deceptive thrust to circumvent his defenses and penetrate the weak part of his armor. It just feels very real and visceral. I’ve never had as much fun playing out combat as in GURPS. It is so fun and immersive that even if you make a couple of combatants in five minutes and throw them against each other, you will have a good time. Great combat stunts feel much better when they are actually performed instead of being a flashy description of an abstract attack.

Aside from all that, I have to mention the disadvantages. And I don’t mean disadvantages of the system, but disadvantages as in negative traits. Remember the flaws that you could take in D&D 3.5 with Unearthed Arcana? GURPS has something like that, but as a central mechanic. While there is a large list of disadvantages that range from liking color green to being blind, I will have to say the following, and not in my words, but in words of an anonymous poster from /tg/, because he put it to words much better than I ever could: A character's personality is usually just defined by flavor in other RPGs. In GURPS, you can have your character's personality mechanically enforced through disadvantages, and you get rewarded character points for it. Some might find this needlessly restrictive to be forced to roleplay your character in a certain way, but for characters that were going to have these personality traits anyway, it's just free points for their player. The real benefit of personality disadvantages is for min-maxers and munchkins that just want to win and might neglect roleplay, just focusing on their stats. For these kinds of players, if they want to be as effective as possible, they need to take disadvantages for the extra points, and most of these will likely be personality disadvantages, which they will be forced to roleplay in certain situations. GURPS literally incentivizes roleplaying with its game mechanics.

Mistaked made when converting from D&D to GURPS

In this post, I will talk about some conversion pitfalls, and how to get into the correct mindset to convert content to GURPS. This does not apply to D&D exclusively, but is relevant when converting anything from any system or medium.

If you’ve been interested in any GURPS conversion, be it D&D, Warhammer 40k, Star Wars, or anything else, you probably know that you cannot find anything definitive. There is always multiple versions of everything floating about, some with minor differences, and some have nothing in common. And that’s absolutely okay, because due to GURPS being, well, generic and universal, no game is the same, and every GM runs their games in their own way – be it tone, power level, genre, or a combination of thereof. You might even see fans arguing about what version is the correct one. I find that silly. If anyone tells me that they would do one of my conversions differently, I’d be like – go ahead and do it! Not in a passive-aggressive way, but in a genuine way. Of course, if I think that the suggested way fits my own view better, then I’d fix my conversion too – there’s always enough room for improvement.

You might have seen people devise formulas to convert, for example, D&D stats to GURPS, and I find that absurd. I believe that the main pitfall of conversion is converting the numbers. For example, I’ve personally seen the following:

A great wyrm black dragon in D&D 3.5 has a natural Armor Class bonus of 36. Full plate armor in D&D grants a +9 Armor Class bonus. That means that a great wyrm has an equivalent of 4 full plate armors worn. Heavy plate armor in GURPS provides DR 9. Four heavy plate armors would provide DR 36. That means that a great wyrm black dragon in GURPS would have scales that provide DR 36. You should understand that D&D and GURPS are absolutely different systems where armor works differently, and that converting it this way is just wrong. Plus, there is no numerical inflation due to absence of levels and Challenge Ratings. And there was no mention of what the GURPS game was even like. If it was over  the top cinematic high fantasy, then maybe DR 36 would actually have worked. If that was intended for something more grounded like the games I run, it definitely would not. Just for the record – GURPS Dungeon Fantasy Monsters 4: Dragons has dragons with DR from 6 to 18, the latter being a super-ancient annihilator dragon.

So, the first and probably the most major pitfall is looking at the numbers. The second, I think, is trying to convert the exact mechanics. I’ve seen people convert spells from D&D and some other sources, such as Dominions 5, and trying to get everything literally the same as in the source material. For example, get the range to be 25 feet and try to make it scale. Or, for example, make an exploding fireball force the victim to roll against DX to take half damage. Both of these are silly, because GURPS does not really have caster levels (although, you can make some spells scale with skill level, for example), and GURPS and D&D work with different granularity in combat. What is a Reflex save to halve damage from a fireball in D&D is just a dive for cover in GURPS. Sometimes the exact mechanics can be ported over to GURPS seamlessly, but often that’s not the case, especially with very gamey mechanics.

Here’s an example – D&D monk’s stunning fist. What exactly is it, and how can you represent it in GURPS? It could be an Affliction that is a follow-up to a punch. It could be an application of the Crippling Blow imbuement skill. It could be the use of the Pressure Secrets skill Or it could simply be a punch to the face, because it forces a stun check. In the latter two cases, you do not even have to port anything – it’s already in GURPS. Can you see it now? We had a quite vague ability that can be translated differently into a system with more granularity in combat. And that’s the thing – you don’t have to convert the exact mechanics, you have to convert the idea of the ability. Don’t stick too closely to the source material! I’ll show you many more examples in the future.

For further reading I recommend checking out GURPS Adaptations – the book that everyone forgets about that covers this topic in a much greater detail. See you next time!

How different is D&D combat from GURPS combat?

GURPS and D&D are very different when it comes to combat, and switching between the two will require a change of mindset. In D&D, a combat round lasts 6 seconds, but GURPS is much more granular, with every second being played out. When in D&D you’d have a standard action, a move action, and a swift action, in GURPS you get one maneuver per turn. You can attack or move or concentrate or do something else. Completely new GURPS players and those who come from the D&D background often feel frustrated that they often “waste” turns. A turn not spent attacking feels like a waste when you come from a system where combat is usually over in 3 to 4 rounds. Archers will feel that even more – now instead of firing five arrows per round, they will get to shoot once every two or three turns. All this might make it seem that GURPS combat is very slow, but if you count how many seconds have passed, you will see that it is pretty fast after all. However, combat might take a long time to resolve in real time, and for that I have one simple advice that applies regardless of what system you’re playing – think about your turn when others are taking their turns. Seriously, there’s nothing difficult in that! I’ve seen some people suggest using a stopwatch to give each player 15 seconds to decide. I think that’s a bit too harsh, but if it works for you – that’s great, I guess. One other thing that is great about GURPS is that if you are an inexperienced player and you have an experienced GM, you can avoid thinking about all the possible maneuvers and options – you can just describe what you want to do with words, and the GM will just tell you how long that will take and what you should be rolling. I’ve already mentioned it, but GURPS is grounded in reality, so if you can do something in real life, you can attempt doing it in GURPS. But in general, do not worry about wasted turns. Sometimes even doing nothing is a legit option.

Another difference that you will notice is that armor works differently. Instead of making it harder for enemies to hit you, it just decreases the damage received. Thus, it works more like Damage Reduction from D&D, but unlike Damage Reduction, GURPS Damage Resistance works against all damage, not just physical. This is something that took me a while to get used to when I switched to GURPS as I always assumed that my fireball would ignore armor. Also, GURPS has hit locations, so you may always elect to attack an unarmored body part, if there is one.

Defenders do not just passively take a beating in GURPS, but can dodge, parry, or block. All this creates a great deal of tactical depth, because you might need to wear an enemy down with multiple attacks to penalize defenses, attack him from the side where his shield cannot block, or try to break his weapon to prevent parrying, if your weapon is heavier.

Positioning also plays a more important role in GURPS. D&D lacks facing, but GURPS does not. And while D&D does reward positioning by granting bonuses to attacks from flanking, this is more pronounced in GURPS. Attacks from the side are hard to defend against, and attacks from the back cannot be defended against normally, which is huge. Also, since you can easily get a nice bonus to defense by retreating, terrain and obstacles play an important role – you might want to corner your enemies.

Since there are no levels, the number of HP your typical human character has does not fluctuate that much. That means that you will not often fight damage sponges, unless, of course, you are fighting something like an iron golem or a gelatinous cube that have tons of HP in GURPS. Every point of damage and HP matters, a sword hit will remain dangerous regardless of how skillful your character is, and a horde of goblins who do not deal a lot of damage individually, will remain a threat. You do not level up and the game does not adjust the enemies for you. I really like this aspect of GURPS, it makes the game much more immersive. There is no Challenge Rating, although there is something like that called Combat Effectiveness Rating in a Pyramid article.

Speaking of goblins. Since GURPS is grounded in reality, small characters usually have low Strength values. So, if you want to be a melee powerhouse as a halfling, you simply will not be. Being small is quite advantageous in GURPS, so if you’d allow, for example, the gnomes to have the same strength as humans, you would probably run into some problems. I have a blog post written about how to get the most out of your low strength, I will cover that topic in more detail later.

What optional rules do I use when playing D&D-style games in GURPS?

As you probably know, GURPS basically consists of dozens upon dozens of optional rules, and it might be difficult for a new GM to pick out the ones that are required for the game they have in mind.

First, I'll say that when it comes to D&D-style games, I am striving for heroic realism, which is similar to what GURPS offers by default. Nothing too gritty, but not very cinematic either. I actually find that using some of the "realistic" rules often allows for cool feats for the characters that would be impossible in a cinematic game. For example, removing an enemy's armor by cutting the straps - isn't that great?

On page 420 of the GURPS Basic Set we have a box with three optional rules:

1. Bleeding. I like this rule, as it makes the First Aid skill more important and makes low Strength enemies still dangerous if they have non-crushing weapons. Thus, a cut from a goblin’s axe might not deal that much damage by itself, but will bleeding out will be an issue.

2. Accumulated Wounds. This one adds a bit more bookkeeping, but I really like this rule. Again, it makes it possible for low strength opponents to cripple your limbs. And if you play a low ST character, then you will be able to, for example, cripple an ogre’s foot if you hack at it repeatedly.

3. Last Wounds. Honestly, I always forget about this one, but I don’t think it’s a bad rule for D&D-style games.

Changing Posture in Armor (p. B395) makes heavily armoured and lightly armoured fighters slightly different. It's a small rule, but it's a nice one.

Damage to Shields (p. B484)

Shields are very good in GURPS, unlike in D&D. Making them breakable adds a lot of depth, decreasing the benefits of having a shield, increasing the power of high ST and high damage weapons, and making differences between various shields more pronounced. Sure, it adds some bookkeeping, but I think that it is worth it.

Extra Effort in Combat (p. B357), plus the additional options for it from GURPS Martial Arts makes FP much more relevant to those who do not have any way to spend them on supernatural abilities. It also helps out low Strength characters a lot for that sweet damage bonus.

Next up, we have the entire Combat chapter from GURPS Martial Arts that starts on page 96. I use almost everything from that one. These options add a lot of tactical depth to the game, making combat ten times more fun than it was. Also, I find the rules for penalized multiple active defenses to be critically important. However, what I don’t use from that chapter is Harsh Realism for Unarmed Fighters (p. MA124). Monks and other unarmed combatants are my guilty pleasure. Even with heroic realism in mind, they usually are subpar compared to armed fighters, so it makes no sense to make them even worse. Chambara Fighting (p. MA128) and More Cinematic Combat Rules (p. MA132) from the same chapter seems too cinematic for my tastes, but the Special Feats for Cinematic Skills, such as Flying Leap, Light Walk, and Lizard Climb, are fine in my eyes.

Injury and Recovery chapter (p. MA136) from GURPS Martial Arts is something I haven’t used in full yet. I’ve used the new hit locations and extra options for the existing ones, but I would love to try out partial injuries. These will add some extra bookkeeping, but I think I’ll be able to handle it.

GURPS Low-Tech also has a bunch of optional rules that might be relevant for D&D-style games.

For example, My Armor Doesn't Fit! (p. LT103) makes the Armoury skill in adventuring situations occasionally useful! And I’m all for additional uses of skills.

Blunt Trauma and Edged Weapons (p. LT102) makes high ST and weapons with high damage bonuses better, and makes armor better too. It's a great rule that everyone should use, I think.

There’s also Harsh Realism for Ranged Weapons (p. LT75), but I prefer not to use it. Ranged combatants usually have it rough on low TL battlefields, so I think it is fair to not impede them further. However, these do not add any bookkeeping, so if you feel that your archers are too strong, feel free to use this rule.

GURPS Low-Tech Companion 2: Weapon and Warriors not only is a very interesting book to read, but also a book that introduces some new rules that range from very optional to essential. This is the book that is basically necessary for D&D-style games because it has rules for scaling weapons and armor for creatures of different sizes. And you know that D&D has dwarves, halflings, giants, and all that. There’s also some really nice rules for weapon, shield, and armor customization (including spiked shields and armor – a D&D staple). I like using the Damage to Weapons (22-24) and Damage to Armor (25) rules from this book. They add a lot of bookkeeping, but they really add a lot of depth to armor and weapon choice. I probably would not use these rules in my normal games, but if you are playing, for example, play-by-post, then the additional bookkeeping is not an issue, as it will not slow down the game significantly. This book also has some exotic weapon that are probably familiar to D&D players, such as the spiked chain and double-ended sword. For the latter and other double weapons, I would suggest using GURPS Fantasy-Tech 2: Weapons of Fantasy instead, as it is more recent, and has more rules, more guidelines, and more premade weapons.

That’s it for optional rules, but I should also talk about some optional systems. For example, GURPS has not one, but four different grappling systems. Personally, I have nothing against the default one, so that’s the one I use. Grappling comes up very often in my games (and GURPS grappling is so much more fun than D&D grappling), and I haven’t seen any glaring issues with the default grappling system yet.

A special mention should go to GURPS Dungeon Fantasy 16: Wilderness Adventures – this book is a godsend even if you’re not playing Dungeon Fantasy. Consider buying this one if you want more detailed rules on camping, foraging, tracking, survival, and all that sort of stuff.

If you strive for heroic realism, then you might want to ban certain advantages too. For example, this is my list: Gadgeteer, Gizmo, Gunslinger, Heroic Archer and its variants, Foresight, Rapier Wit, Serendipity, Social Chameleon, Weapon Master (but not Trained by a Master). These are way too cinematic for my tastes. Also, I have some gripes with Weapon Master. Peter Dell'Orto has put it into words more elegantly than I would ever be able to in one of his blog posts that I will link in the description. In addition to those issues, I feel that Weapon Master makes encounter balance much more difficult. Generally, you know how much damage a fighter can do on average, but Weapon Master creates an entire new category to take into account. An armored enemy with a certain level of DR might be impervious to a fighter without Weapon Master, but the same DR might be almost unnoticeable by the fighter with Weapon Master. This isn't cool. However, if you want a more cinematic D&D game, feel free to use all of these advantages. I will not judge you.

GURPS also has two different published Strength tables – the default one and the Knowing Your Own Strength one. There are many various fanmade ST reworks, out of which Reduced Swing Damage is probably the most well-known one. I will link it in the description. I’ve played with these three, and all of them are good. For D&D-style games I would recommend either using the default one or Reduced Swing Damage. Knowing Your Own Strength works better for modern day and sci-fi games, in my opinion.

Weapon Master - https://dungeonfantastic.blogspot.com/2021/06/weapon-master-creates-havehave-nots.html

Reduced Swing Damage - http://noschoolgrognard.blogspot.com/2013/04/adjusting-swing-damage-in-dungeon.html

What magic system to use for D&D-style games?

In this script, I will give a short overview of the various magic systems in GURPS and talk about which one I prefer for my D&D adaptation and why. This won’t be a detailed delve into the topic, but if you want an in-depth overview consider watching the first episode of the Only the parts you need podcast.

GURPS has a variety of premade magic systems for you to choose from, but it also has GURPS Powers and GURPS Thaumatology books that will help you create your own magic system. I think these two books are essential reading for those you want to get GURPS. That aside, let’s start with basic Magic, also known as vanilla Magic or Magic-as-Skills. This is the system that you can find in the GURPS Basic Set in its short form, and in GURPS Magic in its proper form. Each spell is a skill, and spells have a prerequisite tree. Spells generally are balanced by their casting times and costs. In short, here are the pros and cons of it in regards to D&D adaptation:

+:

1. It’s likely to be known by players, as it is the default system from the GURPS Basic Set.

2. A lot of support in published supplements.

3. It’s likely to be simple to grasp for new players coming from other fantasy RPG systems.

4. A lot of options and tweaks in GURPS Thaumatology to enhance the flavor.

5. Is a ready-to-play system with everything worked out. The GM can just say “we’re using the default magic system” and the players will know what he is talking about.

6. Has something of a scientific flavor due to its prerequisite tree.

7. Relatively low character point investment.

-: 

1. Players can be daunted by the huge spell list.

2. Might be too fixed for the players’ or GM’s taste, even with the options from GURPS Thaumatology.

3. Quite a lot of bookkeeping.

4. Guidelines for new spell creation feel lacking.

5. Experienced players tend to stick to the “cookie-cutter” builds.

6. Has absolute effects that are likely to be holdovers from the previous edition. (This and many other issues are tackled in the Unofficial GURPS Magic Errata).

7. Character point investment might be too low. Spell costs are in no way consistent with the advantages and disadvantages as they use different frameworks.

8. Honestly, in my experience, it kind of upsets the game balance, and players coming from D&D spellcaster supremacy will be sad to see GURPS caster supremacy.

I tried using Magic-as-Skills for D&D-style games, and it did not really work out well. Personally, I like the feel of this system, I really have a soft spot for it, but my experience has shown me that it’s better to use something else.

The next one is Ritual Path Magic and Incantation Magic. I’ll clump them up together because they are derived from the same chapter of GURPS Thaumatology and work very similarly. In short, you have path skills and several effects. To cast a spell, you combine paths and effect. For example, a spell that destroys weapons might be a combination of the Destroy effect and the Matter path. Thus, it is a Destroy Matter spell. Then you either accumulate energy over time, or make a casting roll at a penalty, depending on which system you are using, and the spell is done. It’s actually much more involved than that, but the details are outside the scope of this video.

And here are the pros and cons:

+:

Very flavourful, and the flavour can be changed to accommodate your requirements.

Very flexible, can accomplish almost anything.

Has support outside of its book (Pyramid #3-66 is the best example).

-:

High character point investment.

Very steep power curve, casters will easily overshadow other party members.

Mechanical complexity.

The list of premade rituals is quite short.

Requires a lot of GM oversight.

Requires a group of players that are okay with the GM vetoing their rituals, with working together with the GM. In general, there must be a great degree of trust between the players and the GM.

I have tried using RPM for D&D-style games, and it was a complete, utter disaster. My experience can be summed up as follows, in the words of an anonymous /tg/ poster:

“You ask the GM if you can cast a spell that does a thing. The GM thinks about this and tries to see if it has any sort of horrible abuses or effects on the setting or other ramifications. He is incentivized to downplay the power of your spell, or to restrict it arbitrarily in some way, which the player will argue against as it is unsatisfying. This conversation continues until one party or the other gives up, or is somehow satisfied, and then you gather the energy required to cast the spell and make your rolls to cast it. You’re probably going to generate quirks while doing so, so the GM has to come up with interesting ways for the spell to mess with you. Ten sessions later, the spell’s impact is realized in a completely unrelated way on the setting and suddenly everything is thrown off track by it. The GM has to have the magic police come in and break arms to make sure nobody does that again.”

This might sound like an exaggeration, but it really isn’t.

The two major problems are magic being too flexible, and magic being too powerful. I could ramble on this topic for a long while, but instead, I’m going to link two blog posts in the description written by Mailanka, who is much better with words than I am. Seriously, give them a read, these posts are enlightening.

My problem with flexible magic systems - https://mailanka.blogspot.com/2019/04/rant-my-problem-with-flexible-magic.html

The Strength of Weak Magic - https://mailanka.blogspot.com/2021/01/the-strength-of-weak-magic.html

Speaking of flexible magic, we have some more systems that fit that definition – symbol, syntactic, and realm magic. Unfortunately, they received very minimal support after their introduction. They feel very barebones in GURPS Thaumatology, like something of an afterthought. There are some similarities with RPM in terms of the systems being flexible, but in terms of power, they seem underwhelming and sometimes poorly defined. Realm magic and symbol magic seem fascinating to me, but they do not really fit my view of D&D. Outside of that, I think there’s a lot of potential there.

Finally, we have Magic-as-Powers, a concept that is introduced in the Basic Set, but it given a much more thorough treatment in GURPS Powers and GURPS Thaumatology. There’s at least five worked example built upon this framework – GURPS Psionic Powers, GURPS Thaumatology: Chinese Elemental Powers, GURPS Powers: Divine Favor, GURPS Powers: Totems and Nature Spirits, and GURPS Thaumatology: Sorcery. Basically, you just build your powers, be they magical spells, divine prayers, chi techniques, psionics, or literally anything else – even mundane abilities such as being able to don armor more quickly – as advantages with appropriate modifiers. It sounds very simplistic, but I cannot emphasize enough just how customizable it is. You can do anything, and have dozens of spellcasting traditions made using this framework that still feel very distinct from each other. Also, since it uses the existing advantage framework that every character uses, it preserves the internal balance. Sure, it is possible to build some broken stuff, or have a certain magic type be significantly more powerful than others, but it is much easier to adjust things. I highly recommend reading the entirety of GURPS Powers, not just the advantage section, because there’s a lot of material on how to build powers, how to run game with powers, and how to customize powers. In my experience, this is the best magic system for D&D adaptations, as it is infinitely customizable, internally balanced, and it makes spellcaster supremacy much less prevalent or even nonexistent. The downside is that it does require some degree of system mastery to get things right, but it comes with experience, so don’t worry about it too much.

How is magic structured in GURPS compared to D&D?

This is mostly intended for people who are not very familiar with GURPS, but there might be some useful information for the veterans as well.

If you’ve ever played D&D, you probably know that all spells are split between eight magic schools, with only a handful double-school and universal spells. The schools are abjuration, conjuration, divination, enchantment, evocation, illusion, necromancy, and transmutation. GURPS has a structure that differs a lot from what you have in D&D.

All spells belong to one of 24 magic colleges, with many of them belonging to multiple colleges at the same time. The colleges are: Air, Animal, Body Control, Communication and Empathy, Earth, Enchantment, Fire, Food, Gate, Healing, Illusion and Creation, Knowledge, Light and Darkness, Making and Breaking, Meta-spells, Mind Control, Movement, Necromantic, Plant, Protection and Warning, Sound, Technological, Water, and Weather. Note that D&D enchantment and GURPS enchantment are different things. D&D enchantment is closer to GURPS mind control, and GURPS enchantment is concerned with enchanting magic items.

Overall, even if you are not playing with magic-as-skills, this college structure is useful for the purpose of limitations imposed on various advantages, such as Sorcerous Empowerment. And this is important, because if your spellcasting tradition allows improvisation, then you really should limit its scope. For example, the default Sorcery assumes no scope limitation and will basically let you cast any spell via hardcore improvisation given enough points in Sorcerous Empowerment and fatigue points to mitigate the penalties. This can get out of hand quickly, bringing you back to the epoch of wizard domination that made everyone else feel inferior. Limiting the scope to no more than four colleges is a good idea. Four colleges is still a lot, but not enough to make the sorcerer a universal problem solving tool. Sometimes you can make the scope wider, but then you should apply other, significant limitations. I will talk about that when I get to recording my wizard video.

If you do not like this framework, you can read the guidelines in GURPS Thaumatology to create an alternative. I mostly stick with the default college structure, but make some alterations:

1. Pyramid #3-91 expands the Metal sub-college of the Technological college into a separate college. I really like that one, so I add Metal as a separate magic college and excise all metal effects from the Earth spells.

2. GURPS Magic: Plant Spells introduces the variant Fungus college. I use it too, just to make surface-dwelling druids feel a bit different from the Underdark druids that live in the mushroom forests.

3. I also introduce some colleges of my own making - Poison, Time, Gravity, Force, and Spirit. Poison and Time are quite distinct from the rest. Force borrows many spells from the colleges of Movement and Protection & Warning, adding some new spells into the mix. Gravity has many intersections with the Force college, but it still maintains a distinct feel. Spirit is a variant of the Necromantic college, mostly intended for shamans. It removes some death-related spells, but add some other soul-related spells that were not in the Necromantic college.

4. The Ley Line college that is suggested in GURPS Thaumatology: Urban Magics does not exist as a separate college – its spells are spread out across other colleges as suggested in the aforementioned book.

5. Some spells in GURPS are classified in a way that doesn’t make sense for D&D. For example, such spells as Banish, Hellspawn, and Summon Demon belong to the Necromantic college. To make things consistent with D&D assumptions, I move them to the Gate college that deals with all extraplanar things. Lend Energy, Recover Energy, and Share Energy can be learned not only as Healing spells, but also as Meta-spells. However, Bless, Curse, and Vigil are removed from the Meta-spell college and are only accessible to divine spellcasters. Create Animal and Create Mount are moved from the Illusion and Creation college to the Animal college.

6. I also allow limited versions of Plane Shift and Plane Shift Other that send the subject to one of the elemental planes to be learned as Air, Earth, Fire, or Water spells instead of Gate.

7. Mind Control spells in GURPS Magic can only affect sapient beings with free will. This is absent in Sorcery, but I do not like that. Thus, I apply Accessibility, Only on sapient beings, -10% limitations to all Mind Control spells. This makes Mind Control spells unable to affect golems, zombies, robots, and animals, making the college less universal. And that’s good, because Mind Control is one of the biggest and most versatile colleges as is.

There's also spells that do not belong to any college. These consist of spells that just do not feel thematic enough to assign to a college. For example, where would you put Evard’s Black Tentacles? Some of them may be accessible to wizards who have no scope limitation, and some of them have a divine nature (for example, Sense (Ethical Category)) that are only available to clerics and other divine spellcasters.

Some of the "double" colleges can be split. For example, Illusion and Creation is a quite small college whose spell grouping might not make sense for some games. In such games, you should be able to split it into the Illusion college and the Creation college. However, you'd have to expand the spell selection. Or, for the purpose of limitations, you can treat any "half"-college as, well, half a college. Light and Darkness can be split in two. Making and Breaking too (however, there's more Making spells there than Breaking ones). Protection and Warning can be split, but I wouldn't do that. Communication and Empathy probably shouldn't be split either.

If we open up GURPS Grimoire for the third edition, we will see some suggestions about moving all the electrical/lightning spells from the Air and Weather colleges into its own Lightning college. The book also suggests splitting the college of Water (it's a huge one!) into three - Water, Ice, and Acid. I'm strongly considering doing just that.

And now let’s go back to the D&D magic schools. You can approximate their values and thus, for example, make a specialized conjurer or abjurer.

Abjurations are protective spells. They create physical or magical barriers, negate magical or physical abilities, harm trespassers, or even banish the subject of the spell to another plane of existence.

In GURPS terms, this covers the entirety of the Protection and Warning college, plus Banish, Resist Fire/Cold (why aren't they Protection and Warning spells?) and all the anti-magic Meta-spells. P&W is a quite large college of magic, so I think that the additions make it closer to two colleges. So, I would count Abjuration as two colleges (-30% for Sorcerous Empowerment).

Each conjuration spell belongs to one of five subschools. Conjurations transport creatures from another plane of existence to your plane (calling); create objects or effects on the spot (creation); heal (healing); bring manifestations of objects, creatures, or forms of energy to you (summoning); or transport creatures or objects over great distances (teleportation).

This school is a mess. First, it's sometimes hard to differentiate between what is the difference between evocation and conjuration. Also, D&D 3e for some reason moved the healing spells from necromancy to conjuration.

But anyway, the summoning and calling spells are covered by Planar Summons and Create/Summon Elemental. Object creation (and also another form of summoning) is covered by the Creation part of the Illusion and Creation college.

Healing spells are the Healing college.

Transportation is the Teleportation and Plane Shift spells. It seems that this with the summoning spells pretty much encompasses the Gate college.

Matter creation is covered by such spells as Create Acid, Create Air, Create Earth, Create Ice, Create Steam, Create Water. Offensive creations would be Rain of Acid, Rain of Ice Daggers, Rain of Stones, Ice Dagger, Stone Missile, Ice Sphere.

Thus, this is three colleges (-20%). If you want to exclude healing spells, this will be equal to two colleges (-30%).

Divination spells enable you to learn secrets long forgotten, predict the future, find hidden things, and foil deceptive spells. That's just the Knowledge college. So, -40%, as for a single college.

Enchantment spells affect the minds of others, influencing or controlling their behavior. That's just the Mind Control college. So, -40%, as for a single college.

Evocation spells manipulate magical energy or tap an unseen source of power to produce a desired end. In effect, an evocation draws upon magic to create something out of nothing. Many of these spells produce spectacular effects, and evocation spells can deal large amounts of damage.

This covers most Missile spells except for those that create something and then launch it (like Stone Missile, Ice Sphere, Ice Dagger, and most Rain of X spells). Again, sometimes it is difficult to understand whether a spell is conjuration or evocation.

So: Acid Ball, Acid Jet, Air Jet, Ball of Lightning, Breathe Fire, Breathe Radiation, Breathe Steam, Burning Death, Burning Touch, etc.

This covers most of the Fire college plus some spells from other colleges. I think it should be close to two colleges, so I would assign a -30% limitation to evokers.

Illusion spells deceive the senses or minds of others. They cause people to see things that are not there, not see things that are there, hear phantom noises, or remember things that never happened.

Obviously, that's the Illusion part of the Illusion and Creation college. Also, some spells from the Communication and Empathy college will fit - Hide Thoughts, Insignificance, Presence; and some spells from the Light and Darkness college - Colors, Remove Shadow, Remove Reflection, See Invisible, Blur, Hide, Invisibility. I think that's enough to count as a single college, so -40%.

Necromancy spells manipulate the power of death, unlife, and the life force. Spells involving undead creatures make up a large part of this school.

That's the Necromantic college (-40%). On the other hand, if you want to capitalize on the life force aspect, like AD&D did, then it would be reasonable to also add the Healing college, which will decrease the limitation value to -30%.

Transmutation spells change the properties of some creature, thing, or condition.

This covers most of the Body Control college, a large part of the Making and Breaking college, plus a lot of matter transmutation spells from other colleges, such as Water and Earth. Honestly, this is so versatile that I would treat Transmutation as three colleges (-20%).

What books do you need?

Obviously, you will need the GURPS Basic Set; you cannot play GURPS without it. If you are an inexperienced player, I suggest reading the introduction as it explains well what GURPS is and what you should expect from it. After that, read chapter 1 of GURPS Basic Set as it details the basics of character creation. Then skim chapters 2-4. They are very big, you do not have to read them all, as there’s a lot of content that simply is not necessary for this type of setting.

After you’re done with that, you should have a general impression of the building blocks of GURPS. However, I strongly recommend also reading How to be a GURPS GM (chapters 1 and, optionally, chapter 6) and How to be a GURPS GM: Managing Expectations (this is a very short book, read it in its entirety). Despite having “GM” in the titles, they are very useful for players as well. These books will help with certain misconceptions about the system and will also help you create a good decent character. The best thing is the guidelines on what attribute and skill levels are considered good and bad – as a new player, you probably have no frame of reference for those.

Now, let’s talk about the other essentials:

- GURPS Martial Arts. This book greatly expands the combat system. Even without it, the combat system of GURPS can be deep and detailed, but in my opinion some of the expansions from GURPS Martial Arts are essential if you want to have even more fun in combat.

- GURPS Low-Tech. This book can serve as a gear catalog for low-tech games. GCS has a library that includes all gear from this book and its companions. Thanks to that, equipping your character is not that hard.

- GURPS Low-Tech Companion 2: Weapons and Warriors. Unfortunately, this book hides rules for scaling gear for small and large creatures. Since D&D is full of non-humans of different sizes that range from halflings to giants, these rules are essential if you’re playing a dwarf, for example.

- GURPS Low-Tech Instant Armor. This is only necessary if you do not use GCS. If you do, you can just use this book’s library to buy piecemeal armor. Calculating armor weights and costs might be tedious otherwise.

- GURPS Powers. If you decided to play a character with supernatural powers, you probably should ask your GM about how these powers work. If you’d like to delve into the details, you can check this book out. But it’s very much possible to, for example, play a sorcerer even without reading it. Ask your GM to explain the sorcery mechanics – they aren’t long or difficult – and use premade spells. You do not have to know all the modifiers and underlying mechanics – the spell’s description tells you what the spell does.

- GURPS Dungeon Fantasy 16: Wilderness Adventures. This book is very important in D&D-style games, as it has many rules about camping, navigation, foraging, hunting, and other things like that. I count it as an essential volume.

Aside from the essential books, you might want to at least consider some other books.

- GURPS Action 2: Exploits. I know that this seems to be absolutely unrelated to D&D, but there are cool chase sequence rules that might be useful.

- GURPS Boardroom and Curia and GURPS Dungeon Fantasy 17: Guilds might interest you with rules about guilds and other organizations.

- GURPS Dungeon Fantasy 8: Treasure Tables and GURPS Dungeon Fantasy Treasures 1: Glittering Prizes are excellent resources about treasures of all kinds.

- GURPS Fantasy is a good read if you want to build your own fantasy setting.

- GURPS Fantasy-Tech 1: The Edge of Reality and GURPS Fantasy-Tech 2: Weapons of Fantasy might be necessary to cover certain fantasy technologies – from superheavy plate armor and swords filled with mercury to reflecting mirror arrays.

- GURPS Furries might be a good resource if you want to have any beastfolk races in your world. Also, there are some nice combat techniques that can be useful not only for monsters, but also for normal characters.

- GURPS High-Tech and GURPS Ultra-Tech could be useful if you like introducing anachronistic technologies into your game.

- GURPS Horror has an interesting corruption system that might come in handy. It is very similar to D&D taint.

- GURPS Low-Tech Companion 1: Philosophers and Kings and GURPS Low-Tech Companion 3: Daily Life and Economics are excellent expansions for GURPS Low-Tech. Nothing essential, but still full of good stuff.

- GURPS Martial Arts: Gladiators can be used for certain D&D characters.

- GURPS Martial Arts: Yrth Fighting Styles has some neat expansions on combat styles and techniques.

- GURPS Martial Arts: Technical Grappling is an alternative grappling system. It is quite complex on the surface and difficult to wrap your head around at first, but it is not as clunky in play as it seems. Alternatively, consider buying Fantastic Dungeon Grappling, which is a more streamlined version of Technical Grappling.

- GURPS Mass Combat is great if you want to command armies.

- The entire GURPS Power-Ups series is great, but not essential.

- GURPS Psionic Powers presents an excellent framework for psionic powers. If you watched my video on adapting D&D psionics, you know that I basically use this book with few alterations.

- GURPS Psionic Campaigns and GURPS Psis are two often overlooked books that contain not only new supernatural traits, but also advice for both players and GMs that can be useful not only for psionics, but also for other supernatural powers, including magic.

- GURPS Social Engineering. This is only necessary for games that focus on social interactions, but this is an excellent book. I highly recommend it, especially if you want to take the focus away from dungeon crawling.

- GURPS Supers has some new traits and techniques, but its GMing advice might be useful for high-power games.

- GURPS Template Toolkit 2: Races is a great book if you want to create your own racial templates.

- GURPS Thaumatology: Sorcery is a great magic system. You probably know by now that I’m a big fan of using it as a base for different D&D spellcasting traditions.

- GURPS Underground Adventures is an excellent book if you want your dungeon crawling to be more realistic or detailed.

What D&D books are useful in GURPS?

If you’ve played GURPS or if you have heard about GURPS, you probably know that most GURPS books are very thoroughly researched, making them excellent resources even for non-GURPS games. For example, GURPS Fantasy is an excellent worldbuilding book that can be used regardless of the system, and I can say the same about GURPS Space. But what about the reverse? What D&D books can be useful when running a D&D-style GURPS game? I’m going to talk about D&D 3.0 and 3.5 books, as I’m the most intimately familiar with them, but do not disregard other editions, some older books are excellent resources.

First, let’s take a look at the core books. Player’s Handbook doesn’t really have anything useful – everything presented there is strictly mechanical in nature, and most of it already exists in GURPS.

Monster Manuals (all five of them), and other monster books, such as Monsters of Faerun and Fiend Folio, have a lot of material that can be converted to GURPS. They also have some lore pieces that can be adapted to be plot hooks. Personally, I love bestiaries, they really make your imagination run wild, and different fantastical creatures are something I’m looking for. However, they aren’t really necessary for a GURPS game. Remember that I already have the first two Monster Manuals converted.

Dungeon Master’s Guide is, I feel, one of those books that not many GMs have actually read properly. I admit that I used to be one of such GMs. I thought “Ah, I’ll manage to come up with something, I’ll just use Dungeon Master’s Guide for the prestige classes and magic items.” Only some time later I decided to read it from start to finish and I was surprised to see that it’s actually a good book. It has a lot of GMing and worldbuilding advice, helpful tables, and other useful tools that would’ve been handy back in the day. I think that the campaigns chapter of GURPS Basic Set and the “Powers in Action” chapter of GURPS Powers suffer from the same problem – people often ignore them. If you’re looking for GMing advice oriented more at D&D-style fantasy games, then giving Dungeon Master’s Guide is a good idea. Sure, GURPS Basic Set does something similar, but in a more generic way, but there are some bits that GURPS does not have. There’s also a lot of information on adventure design and environments, probably even more than GURPS Dungeon Fantasy 2: Dungeons and GURPS Dungeon Fantasy 16: Wilderness Adventures have. I’m sure that you can easily expand the latter two with stuff from the Dungeon Master’s Guide.

Now let’s go through the rest of the books.

Arms and Equipment Guide won’t be useful to you. Whatever it has, GURPS has got it covered one way or another. The only interesting thing here is various exotic weapons, and I already have converted all of them to GURPS. I think I should make a video on that topic.

Book of Challenges has premade encounters and traps that can easily be adapted to GURPS. It also has sidebars and small sections of GM advice that can be applied to GURPS, such as using anti-magic zones, familiars as scouts, and playing monsters that are smarter than you are.

Book of Exalted Deeds and Book of Vile Darkness, despite being books about handling good and evil in your games, respectively, actually do not have much interesting in them. Most of the content is purely game mechanical in nature, and you won’t need that in GURPS, unless you enjoy the process of doing the conversion. There are some interesting lore bits, but I am trying to disregard lore when talking about the usefulness of books in this video.

Cityscape is an excellent book even if you are playing GURPS. It describes how to run an urban campaign, how to design cities, politics, organizations, urban encounters, events, and hazards. Sure, GURPS has some of that in the Basic Set and GURPS City Stats and Boardroom and Curia, but Cityscape is a much more extensive volume. I highly recommend giving it a look if you are planning to run an urban fantasy game.

Complete Adventurer is mostly a mechanical supplement. Sure, it does have an organization building chapter at the end, but it’s basically the same as GURPS Dungeon Fantasy 17: Guilds.

Complete Arcane, however, has an interesting chapter on GMing a campaign focused on spellcasters and worldbuilding around magic. Other than that – it’s just mechanics.

Complete Champion not only has the usual mechanical bits, but also describes how to design organized religions in fantasy games. For example, it will tell you what the clergy of a deity of knowledge does, what the goals of a church or a deity of law is. It’s pretty nice. Complete Divine adds some more notes on organized religion, but not much else.

Complete Mage has some character creation advice that can be useful to GURPS players as well. It describes spellcaster archetypes, what kind of role they play in the party, and what kind of spells they should get.

Complete Psionic is widely considered to be a very low-quality supplement. And I have to agree with the common opinion, which is a shame because I really like psionics. Some lore bits here are alright, but some of them make absolutely no sense. Even the mechanics here are very questionable, but that’s not our problem.

Complete Scoundrel doesn’t really have much going for it. Neither does Complete Warrior, because GURPS Martial Arts exists.

Defenders of the Faith was often forgotten by D&D players. After all, why use a 3.0 book when there’s Complete Divine and Complete Champion for D&D 3.5? However, Defenders of the Faith has a lot of material that did not get updated in the aforementioned books, such as advice for playing clerics and paladins, more good stuff about creating churches and religions, and even guidelines for running a temple.

Deities and Demigods is a very good worldbuilding book. I have not read GURPS Religion for the third edition, but it probably discusses the same topics.

Draconomicon is full of both interesting mechanics and lore, but there is nothing that can be used in GURPS right out of the box. You will have to convert stuff.

Dragon Magic is mostly a mechanical volume, but it does have an interesting chapter with worldbuilding and adventure design advice if you really want to focus on dragons. But GURPS Dragons has the same thing.

Drow of the Underdark, Fiendish Codex I and II, Races of the Dragon, Races of the Wild, Races of Stone, and Races of Destiny are mostly lore books, let’s ignore them.

Dungeon Master’s Guide II is another excellent book for GMs. Adventure design, campaign design, worldbuilding, different play styles, how to deal with problem players, how to make NPCs. Again, almost everything in this book can be used in your GURPS games, this is definitely a good book.

Dungeonscape is a book about dungeon design. Basically, it’s the same as GURPS Dungeon Fantasy 2: Dungeons, but much more comprehensive. Another good one, in my opinion.

Elder Evils is basically a collection of adventure modules. These probably won’t be useful to you, as adapting a D&D module to GURPS is much more difficult than converting a monster or ability.

Enemies and Allies is a collection of NPCs. More or less useless for GURPS games.

Epic Level Handbook is mostly full of game mechanics and its GMing advice is not compatible with GURPS.

Exemplars of Evil is a book about villains. Not only does it have some examples, but it has a nice chapter on designing villains, and it can be used in GURPS as well.

Expanded Psionics Handbook is completely unnecessary. It’s a great D&D book, but not a good GURPS book.

Frostburn, Stormwrack, and Sandstorm are three environmental books. Despite being among my favorite D&D books, they are not useful in GURPS at all.

Heroes of Battle is a book on warfare. While at first it seems like something of a minigame book, it actually has some decent advice on how to incorporate the PCs in warfare campaigns and how to design adventures around that.

Heroes of Horror is a decent book, but GURPS Horror is even better.

Libris Mortis is something like Draconomicon, but for the undead. Not needed for GURPS games.

Lords of Madness is another book that is mostly lore. I love this book, but it doesn’t bring anything new to a GURPS game.

Magic Item Compendium, Spell Compendium, and Rules Compendium are just compilations of magic items, spells, and rules. Not really necessary for GURPS games.

Magic of Incarnum introduces a new magic system. While I have a GURPS conversion of it, it’s one of my oldest ones, and it is a mess that needs a rework.

Manual of the Planes and Planar Handbook are fantastic D&D books, but useless for GURPS games.

Unlike Defenders of the Faith, Masters of the Wild, Song and Silence, Sword and Fist, and Tome and Blood are D&D 3.0 books that were updated almost entirely in Complete Adventurer, Arcane, Divine, and Warrior.

Miniatures Handbook should be ignored, even though it’s an underrated D&D book, in my opinion.

Player’s Handbook II has some interesting character building advice, but other than that, not much else to say.

Savage Species has some campaign-building advice for games where the characters are monsters.

Stronghold Builder’s Guidebook contains everything you need to know about castles and strongholds. It actually might be useful for GURPS players, even though numbers will require some adjustments.

Tome of Battle, Tome of Magic, and Unearthed Arcana introduce new subsystems and variant rules. It’s all mechanics, so it’s not useful for GURPS games.

And that’s it – as you could see, I omitted setting-specific supplements and adventure modules. I think I should also give an honourable mention to World Builder’s Guidebook – an AD&D worldbuilding supplement that is extremely good. I used it a lot when designing my own setting. Other than that, I should say that Dragon Magazine often has very interesting articles even in the old issues that can be easily used in GURPS as well.