Terrain Hazards: The Cave

Look at all those potential hazards!

This is a bit of an idea I've been rolling around in my head for a short while now. I like making fights challenging in ways that aren't just "This is the same fight as before, but since, lemme see, you last fought this at x character points, and you have accrued delta x character points so the enemy now has f(Δx) additional striking st, hp, and DR. Maybe other people are great at this, and it's only my problem, but a lot of fights on tactical mats for me are just "you are in a big room with... this many things you need to walk around," which feels like I am doing the game a bit of a disservice.  So let's take a look at some dungeon archetypes, borrowing headers from Dungeon Fantasy 2, and what kind of things we can easily add to a fight to give it just a tad more depth.

I am using the archetypes described starting p, 16 of Dungeon Fantasy 2, and the descriptions, while evocative and suggestive of some of the appropriate conditions that one would typically run into while

Some special rules for jumping
and material hardness can
be found here.

exploring them, I plan on going just a bit further by stealing analyzing ideas from TV Tropes and seeing if I can create a small grab and go list of little details to make fights more mechanically interesting. For a cave, the following tropes are commonplace.

Stalactites (The guys on the ceiling)

But most rules can be found
here in an easier form.

The first thing we want to do when we see stalactites is think of some way to knock them down. You can calculate the weight of a stalagmite from p.558 of the basic set, and falling velocity from p.431. Using both of these for example, and then fiddling with the numbers to my liking, I figure a 3d Impaling damage stalactite is about 5 yards up (high ceiling?) and about a half foot thick at its widest, and requires 52 HP of damage to fall, a lot of damage, but perhaps it can be used in a trap, or serendipity can be used to find one that is already somewhat weak? A less amazing one might only need 12 HP of damage to knock loose, and at the same height, do 1d crushing damage. Still not a particularly good trade off damage wise, unless maybe you can use an area of effect attack to hit several at once, doing way more damage than 12 HP would do to a single given target. Otherwise, perhaps it might be extra damage if it is guaranteed to hit a skull location, or be difficult to dodge (enemies can't use active defenses against things they can't see.) 

Stalagmites (the guys on the floor)

Large stalagmites are not going to likely be trap in of themselves but they can be used for cover and deception. Characters with large preparation times such as spell casters or crossbow users can put these to good use, with very little fear of being hurt from over-penetration. Likewise, sources of light that would generally brighten a whole room can be easily obstructed. A GM might want to assess a small skill penalty for projectile weapons that need to shoot through a space occupied by stalagmites.

Pits

Pits can be found in a lot of places, but natural caves especially can have many. Pits, used properly can legitimize a bunch of strategies not normally exploitable. 

Simple knock-back can immediately become fatal on thin ledges, making blunt crushing weapons very useful in a cave.

Interestingly shaped pits can have interesting effects on clearance. A typical unencumbered hero that has two turns to jump can probably clear a 3 yard pit; and one that has a running start might be able to clear a 6 yard pit. Jumping calculations can be found on p. B352 in the basic set. When making dangerous jumps during combat where DX is required, failure means a fall that isn't dangerous (I interpret this as reaching the other side, and immediately falling forward,) a critical failure does have damaging repercussions (you might fall into or slide down the side of the pit you just attempted to leap).

For a GM that might be a little more forgiving, the pit can of course be replaced by a large body of water.

Narrow Winding Pathways

In narrow passages, weapons with a wide swing might not be able to work. In a passage less than 3 yards wide, swing weapons with a reach of 2 do not work right, and in passages less than 2 yards wide, only thrusting attacks will work. Passages less than 1 yard wide can make it necessary to remove rigid heavy armor before going through.

All of these problems become much more interesting when dealing with enemies with interesting morphologies. An SM-2 creature that uses weapons might not feel any stress in a 1 yard wide tunnel; a horrific SM+3 monster might not be able to follow heroes into a 1 yard wide tunnel.

Paths that wind can remove the efficacy of ranged weapons that need line of sight to work. Round bends can either allow the party to escape a hoard of skeleton archers, or let someone get away from the party crossbowman.

Knock-back is also useful here as well. Slamming an enemy into a wall means that they take slam damage against themselves.

Puddles

Special mention should be given to this nigh innocuous trapping of underground caves. Caves lend themselves to stealth tricks which usually leads to back-stab trickery or setting traps. Puddles however can help give some auditory inclined cave fauna a pinpoint to your location. Something that seems like a small detail, suddenly can blow a grand scheme. A player might counter it with a use of Light-Walk skill though.

Other Thoughts and Conclusion

I've not read it, but Underground Adventures could have some information in the same vein as this post, and it was recommended to me while brainstorming ideas. This is a first in a series I kinda been playing around with. It's a bit of a slightly mechanically exploratory terrain for me, but I'd like a catalog of easy to drag and drop complicating factors for battling in different terrains. It's hard to put to words what I specifically want to document, but the point of this series are obstacles that have an immediate real effect on combat that make it into something besides "kill all the guys in whatever order they come at me."