Bad Footing/Terrain in My Games

Bad Footing/Terrain in My Games

Not long ago, I explored the topic of difficult terrain and bad footing in GURPS, and found it to be a mess. So, to avoid any complications and arguments in play, I decided to clearly define what kind of terrain provides what kind of penalties. Rules are subject to change or amendments in the future.

 Bad Footing penalties come in levels. Each level of Bad Footing imposes a -2 penalty to melee and ranged attack rolls, DX rolls to remain standing, Acrobatics, Jumping, Dancing, and all other full-body DX skills, and a -1 penalty to defenses.

SLOPES/STAIRS

Let's deal with inclination first. Inclinations are important when it comes to Combat at Different Levels (p. B402). Don't forget that these rules were expanded on page 5 of Pyramid #3-77. This includes both natural slopes (hills) and artificial slopes (stairs). I had to consult the AD&D Wilderness Survival Guide, AD&D Dungeoneer's Survival Guide, real world staircase angle standards, etc.

Gentle slopes have a tilt of at least 15 degrees but not more than 30 degrees. In the least extreme case, a gentle slope changes 0.77 feet in elevation for every yard of horizontal distance measured on a line that cuts through the slope. In the most extreme case, the elevation changes 1.5 feet for every yard of horizontal distance. If the minutae do not matter, you can treat it as 1 foot of elevation per every yard of horizontal distance. Thus, adjacent fighters of the same height will not get any combat benefits, but those two yards apart will.

    Moving up or down a gentle slope costs +1/2 movement point per hex. When using High-Speed Movement (pp. B394-396), you may elect not to slow down when moving down a gentle slope. In that case, you have to make a DX+3 roll to avoid losing control.

    Bad Footing: 0

Moderate slopes range from 31 degrees through 50 degrees. In the most extreme case, the elevation changes 2.3 feet for every yard of horizontal distance. If the minutae do not matter, you can treat it as 2 feet for every yard of horizontal distance. This way, even adjacent fighters of the same height will receive combat modifiers. 

    Moving up or down a moderate slope costs +1 movement point per hex. When using High-Speed Movement (pp. B394-396), you may elect not to slow down when moving down a moderate slope. In that case, you have to make a DX+1 (DX+3 with -2 for Bad Footing) roll to avoid losing control.

    Bad Footing: 1

Severe slopes range from 51 degrees to 70 degrees. In the most extreme case, the elevation changes 2.82 feet for every yard of horizontal distance. If the minutae do not matter, you can treat it as 3 feet for every yard of horizontal distance. Most fixed ship's ladders count as severe slopes.

    You cannot walk up or down a severe slope, use Climbing instead (p. B349).

    Bad Footing: 2

Most normal stairs that are used to access habitable rooms have an angle between 18 and 38 degrees, so they can be either gentle slopes or moderate slopes. Stairs used to access non-habitable rooms, such as attics and cellars, usually have an angle between 39 and 50 degrees. This is a moderate slope.

SNOW

There are two ways of dealing with snow in your games - realistic and simplified. The realistic rules come from GURPS Russia - each inch of snow is equal to 5 pounds of encumbrance. In addition, snow should provide one level of Bad Footing.

Now let's do the simplified snow rules. Well, it's not as much simplified as more gamified, as not everyone wants to bother with encumbrance.

    Shallow snow (up to 6 inches) - +1/2 movement point per hex. Bad Footing: 1

    Medium snow (7-12 inches) - +1 movement point per hex. Bad Footing: 1

    Deep snow (13-36 inches) - +2 movement points per hex. Bad Footing: 2

    Very deep snow (37-60 inches) - reduces you to Move 1. Bad Footing: 3

    

    Snow any deeper than that requires you to dig through it. The depths listed here are for SM+0 upright creatures, like humans. For anyone else, the depths are proportional to their heights. For example, for a SM+0 human (~2 yards, p. B19) snow 7-12 inches deep is medium snow, for a SM-1 dwarf (~1.5 yards), medium snow is 5.25-9 inches deep (x0.75), while for a SM+1 ogre (~3 yards), medium snow is 10.5-18 inches deep (x1.5). Thus, snow 10 inches deep would be medium snow for a human, deep snow for a dwarf, and shallow snow for an ogre.

In addition to all that, we have some extra rules regarding movement and combat on snow.

Snow is crunchy - Stealth takes a -2 penalty, if being heard matters. (This is implied in the description of the mukluks, p. LT98).

Snowshoes (p. LT133) allow movement on top of snow at -1 to Move (Note: this was -2 to Move in GURPS Russia). If you are using the realistic snow rules, then they also remove the extra encumbrance imposed by snow. A snowshoe-wearing character must make a DX or Sports (Snowshoeing) roll in order to use a retreat with an active defense. Failure by 1-3 means the character stays in the same hex - the retreat fails. Failure by 4 or more meants the retreat succeeds, but the character falls on his back after the defense roll is resolved! Moving backward or sprinting requires a DX or Sports (Snowshoeing) roll to avoid tripping.

Skis (p. LT133) allow moving on snow without any movement or encumbrance penalties (Note: this was -2 to Move in GURPS Russia). When moving uphill, halve your Move. Downhill, the rules for gliding flight (p. B56) apply to movement over snow: descending 1 yard adds 1 yard/second to velocity, up to Basic Move x 4. To decelerate, the skier moves onto level ground, where he loses 1 yard/second each turn; on rising ground, he loses an additional 1 yard/second per yard of ascent. Deceleration stops when he’s at normal level or uphill speed. A skier may brake more aggressively, making a DX-based Skiing roll at -1 per 5 yards/second to stop in one second; he may travel up to his Basic Move while doing so. Anyone within 3 yards downhill of him must make a Dodge roll or be blinded for 1d seconds by a spray of snow!

    A skiing character must make a DX-2 or Skiing-2 roll in order to use a retreat with an active defense. Failure by 1-3 means the character stays in the same hex - the retreat fails. Failure by 4 or more meants the retreat succeeds, but the character falls on his back after the defense roll is resolved! Moving backward (but not sprinting) requires a DX-2 or Skiing-2 roll to avoid tripping. When on skis, a character may not take any facing after a maneuver that allows a step; he is limited to a one hexside change. Any further changes require a Move maneuver.

SLIPPERY SURFACES

Slippery surfaces are treacherous. This degree of slipperiness includes wet or bloodied floors, wet foliage, sleet, mud, and old ice. Those moving into or through the slippery area must roll against DX‑2 every turn or fall; this roll is at +1 if walking at Move/2, +2 at Move/4, and +3 at Move/8 (round down, minimum 0). Critical failure causes 1d‑2 injury to a randomly chosen limb. Outside of combat, if you walk slowly (Move 1), then you only need to make an unpenalized DX roll every four minutes to avoid falling.

     In combat, you have to make a DX-2 roll after each attack or defense roll. Perfect Balance gives +4, Excellent Balance gives +3. Failure means that you fall down.

    If you fail a DX roll to remain standing by 1, you fall on your knees; if you fail by 2, you assume a sitting posture, and any worse failure results in you falling prone. To stand back up after falling down on a slippery surface, you have to make two successful DX-2 rolls in a row. 

    If the slippery surface in question is ice, then you can substitute Survival (Arctic) for your DX; if it is wet foliage, then you can substitute Survival (Jungle); if it is mud, you can substitute Survival (Swampland).

    Slippery surfaces allow skidding (p. MA105). If skidding on ice, you may substitute Sports (Ice Hockey) for your DX.

Bad Footing: 1

Very slippery surfaces include waxed or greased floors and new ice. The rules are the same, but roll against DX-4 to avoid falling. Outside of combat, if you walk slowly (Move 1), then you only need to make an unpenalized DX roll every two minutes to avoid falling.

Bad Footing: 2

Extremely slippery surfaces include oiled floors. The rules are the same, but roll against DX-6 to avoid falling. Outside of combat, if you walk slowly (Move 1), then you only need to make an unpenalized DX roll every one minute to avoid falling.

Bad Footing: 3

Skis can be used on ice as if it were snow for simple forward and overland travel, but fighting on skis makes the character use both the ice combat and ski combat rules!

TL0 bone skates (p. LT133) are primitive. The skater can’t push against the ice with his feet; he uses hand-held wooden poles. Skating Move is half normal land Move. Lack of good traction gives -2 to DX-based Skating rolls to negotiate hazards.

TL3 ice skates (p. LT133) provide much better traction and maneuverability. DX-based Skating rolls to negotiate hazards are unpenalized. The wearer also gains a level of Enhanced Move (p. B52).

WATER

Shallow water is up to 1/6 of your height (1 foot for a typical human). Moving through shallow water costs +1 movement point per hex.

Bad Footing: 1

Deep water is deeper than 1/6 of your height. Water this deep reduces you to Move 1. However, if you have the Cannot Float quirk, then you suffer a reduced penalty, deep water imposes +2 movement points to the movement cost instead of simply reducing you to Move 1.

Bad Footing: 1

I would also impose a -2 penalty to Stealth when moving through water. Splish-splash.

SAND

Packed/wet sand is comparatively easy to walk on. There are no movement penalties.

Soft sand is dry and loose. Very common in desert and beach terrain. Usually is about 1 foot deep. Moving through soft sand costs +1 movement point per hex.

Bad Footing: 1

MUD

Shallow mud is up to 1/12 of your height (6 inches for a typical human). Moving through shallow water costs +1 movement point per hex.

Bad Footing: 1

Deep mud is deeper than 1/12 of your height. Deep mud imposes +2 movement points to the movement cost instead of simply reducing you to Move 1.

Bad Footing: 1

I would also impose a -2 penalty to Stealth when moving through mud. Squelch.

UNEVEN TERRAIN

Certain objects and types of terrain that do not fit any other category may impose an additional penalty. Rocks, corpse piles, loose pebbles, exposed roots, etc. are difficult to move on. Moving on such surfaces costs +1 movement point per hex.

Bad Footing: 1

How large a body must be to count as an obstruction, and how large must it be to count as difficult terrain that imposes a bad footing penalty? Let's say that two bodies of the same SM as the fighter count as a "pile" and become difficult terrain, not merely a minor obstruction (p. B387). One SM+1 body should constitute a "pile" too, and three SM-1 bodies as well.

VEGETATION

Let's combine the rules from GURPS Magic: Plant Spells, Pyramid #3-85, and GURPS Action 5: Dictionary of Danger to create something fitting for D&D-style games. Vegetation has the following density levels.

Sparse vegetation does not impose any penalties at all.

Normal vegetation doesn't impose any penalties in combat. However, while running, roll every 100 yards against the better of DX or DX-based Running to avoid an ordinary mishap (e.g., trip and fall down). Each hex has 25 HP.

Dense vegetation is much more treacherous. Traversing dense vegetation costs +1 movement point per hex. Running through it (Move 3+) requires a DX-2 roll each turn, with failure meaning tripping and falling. All ranged attacks modified by -2 due to automatic cover for targets in addition to bad footing penalties. Additionally, certain characteristics are modified: +3 to Stealth, +2 to Camouflage, -2 to Vision rolls, -3 to Hearing rolls. Each hex has 40 HP.

Bad Footing: 1

Impenetrable vegetation cannot be moved through by SM+0 creatures. It gives -6 to Vision rolls and -5 to Hearing rolls. Creatures small enough to enter (see below), get +4 to Stealth and Camouflage. Each hex has 65 HP. Furthermore, the vegetation acts as a barrier, and it may function as cover from ranged attacks.

Creatures at SM -1 or SM -2 pass through vegetation at one step lower; e.g., a halfling moves through Impenetrable as if it was Dense. At SM -3 or smaller, move down two steps. This applies only to movement through the hex, not skill modifiers or cover. Creatures of SM +1 or greater treat Dense as Impenetrable and Normal as Dense.

SHAKY TERRAIN

Rocking ship or boat is quite difficult to fight on. Moving on such vehicle costs +1 movement point per hex.

Bad Footing: 1

Huge and flat creatures can be climbed on (Pyramid #3-77, p. 10). Running on their bodies costs +1 movement point per hex.

Bad Footing: 1 (or 2, if the creature attacked or dodged on its last turn)

HIGH HEELS

High heels make you move slower (+1 to movement point per hex).

Bad Footing: 1