Fighting, Running, and so forth on a Slope

[Varyon]

Briefly, I'm designing a power that lets a character modify the pull of gravity for himself - basically, he can tilt gravity by up to 85 degrees, although only a 45 degree or so tilt is more likely. As a result, there's going to be a lot of cases where he'll be moving as if on a slope.

I've looked through several of my GURPS books, and the only real mention of doing things on a slope was from DF16, and that didn't really give me the information I needed. Is there a good GURPS treatment of running around on a slope anywhere?

If not, I see there being three considerations for slopes. First off, keeping your footing - a steep slope, or even a less intense one with slick ground, can make it very difficult to avoid faceplanting, particularly while moving around and fighting. At what angle should we start calling for DX/Acrobatics checks to avoid a fall while moving around, and what sort of bonuses/penalties should come into play?

The second consideration is moving up a slope. I saw a mention of this in Tbone's old GULLIVER rules, which ultimately came down to "You and your gear weigh more when moving uphill." Are there any further effects to consider?

The final consideration is moving down a slope. It seems to me that doing so should allow you to move faster than your normal Move, although doing so is likely to call for some Control Rolls. Any thoughts on how to handle this?

[Ulzgoroth]

I'd definitely say that a significant slope is bad footing, with the usual consequence for that. I'd be interested in further adjustments, but don't have any to offer.

[ArchonShiva]

As long as you're bringing up considerations, quadrupeds with shorter forelegs are very good at going up sloes and very bad at going down them, with bears being the best-known example. Humans with free hands can quickly turn into a short-legged quadruped.

[Curmudgeon]

If he's changing only the angle at which gravity affects him personally, I don't see him needing to make acrobatic/DX rolls at all. Put him on a 45° slope and he can change his personal gravity so that he is standing perpendicular to the ground. From his opponent's point of view, he is leading with his head and arms, leaning into the attack. Likewise, his opponent seems to be leaning forward leading with his head and arms.

I'd say that a bad footing penalty would be appropriate for any slope up to about 30°, 45° for stairs, was appropriate. Having been on military obstacle courses, slopes greater than 30° require you to put your attention on moving forward. They're really not something you can conduct combat on easily. The bad footing penalty shouldn't apply to the character with the gravity power and hit location is rolled as 2d and read normally. If for some reason the gravity effect caused him to appear to be leaning back or a rear attack was made while he appeared to be leaning forward, roll hit location as 2d+6.

[Tinman]

I think bad footing should cover it.

[Varyon]

Here's what I've worked out so far:

For keeping your footing, you'll have to make a DX or Acrobatics roll every so often, at a bonus or penalty based on the slope and the action you're taking. Perfect Balance gives its usual +4. Using Control Rolls as a guideline, if a character without Perfect Balance would be rolling at DX+4 or greater, no roll is needed (Control Rolls start at DX+3). I'd imagine that moving at Move/2 on a slope of 45 degrees just barely qualifies for DX+4 (and thus no roll). I'd eyeball cutting Move in half as being worth +2, so that's a base of DX+2. Standing still - good for +4 - at an 85 degree angle is probably DX-10, marking that as DX-14. That's -16 for +40 degrees, implying a -2 per +5 degrees*. Modifiers for actions are probably +0 if going up to Top Speed, +1 if going up to 75% of Basic Move, +2 up to 50%, +3 up to 75%, and +4 if standing still. If you're making melee attacks (or ranged attacks with thrown weapons) or Active Defenses, or are dancing or doing any other complicated physical task, you probably suffer a -4 or so. This is all from a base of DX+20 at 0 degrees. There's a serious concern about how often you need to make such checks, however.

Once such rolls become necessary, you can opt to switch from running around to Climbing, using that skill instead.

*More realistically, the relationship is probably logarithmic. However, our region of interest - 35 degrees and greater - the logarithmic and linear equations give fairly similar results (the logarithmic has 35 degrees as starting at DX+8, while the linear has it starting at DX+6).

For moving uphill, GULLIVER has effective weight doubled when working completely against gravity (90 degree angle). That's probably about right. Every 1 degree shift is a little more than 1% of 90, meaning it's going to be affected by around 1% of the gravity vector - recalibrating 90 degrees as x1.9 to weight makes the math cleaner, where every 1 degree of slope is +1% to weight. If using RAW GURPS, character weight is a Feature, so we shouldn't unduly punish those who opt to have heavier characters (or reward those with lighter characters) - every +1% to weight is instead +8% of BL to weight. Thus, a character with ST 14 (BL 39.2) suffers from an additional 31 lb on a 10 degree slope. Alternatively, ignore character weight and just adjust for gear. If climbing, it's probably appropriate to halve any weight increase (you're using arms and legs instead of just legs).

For moving downhill, you're basically tapping gravity to increase acceleration. A 90 degree angle (falling) results in an acceleration of right around 10. Again, we'll shift things a bit to make the math cleaner, such that every 1 degree is good for +0.1 yards/second/second acceleration (for 1G; multiply this by actual gravity if it's different). Thus, a character running down a 15 degree slope can increase his current Move by 1.5 every second. For Control Rolls, I'm thinking your normal Top Speed doesn't require one, but going any faster calls for at least a DX+3 roll, perhaps at -1 for every full +20% of Basic Move. So, a character with Move 5/10 (thanks to Enhanced Move 1) doesn't roll when moving at Move 10 or less, rolls against DX+3 at Move 11, DX+2 at Move 12, and so forth. He could theoretically go up to Move 20 or even higher, although at that speed he's rolling against DX-5 to avoid tripping! If you're on bad enough of a slope that you need to roll to keep your footing already, require those rolls instead, at -1 per +20% of Basic Move above Top Speed. As with keeping your footing, above, there's still the open question of how often such Control Rolls should be made.

Originally Posted by ArchonShiva

As long as you're bringing up considerations, quadrupeds with shorter forelegs are very good at going up sloes and very bad at going down them, with bears being the best-known example. Humans with free hands can quickly turn into a short-legged quadruped.

This would be a Feature that gives a +n when going up a slope (or down one backwards), -n when going down a slope (or up one backwards). n would be set by relative sizes, but probably wouldn't be more than 2 or so.

Originally Posted by Curmudgeon

If he's changing only the angle at which gravity affects him personally, I don't see him needing to make acrobatic/DX rolls at all.

He can't tilt gravity by more than 85 degrees (and ideally wants to tilt it less than that; the more the tilt, the harder it is to manage and the more he increases the total strength he feels from gravity), so if he's trying to run up a wall that normally tilts toward him, he can't make it too close to flat. Additionally, I needed to work out how running downhill should work, as the ability to tilt gravity to run faster would be rather useful.

Originally Posted by Curmudgeon

I'd say that a bad footing penalty would be appropriate for any slope up to about 30°, 45° for stairs, was appropriate. Having been on military obstacle courses, slopes greater than 30° require you to put your attention on moving forward. They're really not something you can conduct combat on easily.

This is moderately consistent with my above assumptions, although I may be being a bit lenient (running up to Top Speed and swinging a sword around and/or Dodging on a 30 degree angle requires no roll to avoid falling, as it's at a total of DX+4).

[malloyd]

Originally Posted by Ulzgoroth

I'd definitely say that a significant slope is bad footing, with the usual consequence for that. I'd be interested in further adjustments, but don't have any to offer.

By causing you to lean a weird way, and presumably alter the force of your blows, you might be able to avoid (or suffer) bonuses (or penalties) for attacking from above or below you wouldn't otherwise too (actually thinking about it, you might always be *worse* off for that, you're leaning back relative to the guy above you, making you effectively lower when moving uphill, and leaning toward him, reducing your effective height advantage when going down)

One special case to watch out for might be stairs though. If you repitch them so you aren't climbing on them, they aren't *flat* for you, you've added a footing penalty you weren't suffering before in order to climb them faster.

Mostly though ignoring penalties for bad footing (sloped) and makes climbing rolls easier (or unnecessary) for you in situations the GM might otherwise demand them seems like about it. Honestly it doesn't seem like a very useful ability. I'd be tempted to just ignore the gravity technobabble (and those possible extra penalties) and just call it Terrain Adaptation (slopes up to 45 degrees), though that loses any edge it might give you from reducing steeper slopes. Though you could bundle it with a Climbing skill bonus and/or Special Exercises (Lizard Climb).

[Varyon]

Originally Posted by malloyd

*SNIP*

Just to nip this now, I should note that the purpose of this thread is to discuss the effects of slopes in general, not to discuss this particular gravity manipulation ability or its influence on slopes. I wanted information on slopes because of the nuances of the ability, of course, but I'd prefer this result in information that could be of potential use in any campaign, not just those with quasi-Windrunners.

(I will be making a thread that will discuss the gravity power eventually, but that might take a little while)