Thinking about House of Leaves recently made me revisit a train of thought I’ve often engaged in: Specifically, that there are a lot of architectural grandeurs that are avoided by players who use battlemaps because they’re difficult to map on a two-dimensional grid or table. (In fact, even if you don’t use battlemaps I suspect that there remains a subconscious aversion to such forms because most adventure prep still defaults to the presentation of a two-dimensional map.)
A significant example of this, for me, are large helical ramps or stairs:
Small spiral stairs, of course, are easy enough to include. But what I’m talking about are helical structures large enough that you could wage a massive melee on them. Perhaps one could do it with 3D terrain, but it seems far too complicated to render on a 2D battlemap. Which is too bad, because there’s a lot of cool stuff that can happen on a helix:
Awaking from a dream this morning, however, I realized that there was a way that one could map such a structure:
There are two tricks to using this map. First, a square is directly above the identical square two half-circles to the right (and below the identical square two half-circles to the left). Once you grok that, it shouldn’t be too hard to eyeball which sections of the ramp can reasonably see each other. (It will also let you easily calculate distance on the horizontal plane.)
Second, if the ramp has a 1:1 ratio of descent (i.e., it’s descending at a 45-degree angle), then horizontal distance on the map equates to vertical distance in the game world. For example, assuming 1 square = 5′:
The point marked B on this map is 120 feet directly below point A.
Of course, a 1:1 ratio of descent represents a fairly steep ramp. But you can set any ratio of descent you like and then just divide the distance. For example, if you had a more gradual ramp with a 1:4 ratio of descent you could just divide 120 feet by four and calculate that the vertical distance between point A and point B is 30 feet.
Once you’ve got both your vertical and horizontal plane distances, of course, you can use the Aerial Distances table on page 78 of Legends & Labyrinths to figure out the actual point-to-point distance. (Or you could calculate it using the Pythagorean Theorem, of course.)
It should be noted that this method isn’t perfect. Because each “half” of the ramp is horizontally inverted there’s a definite spatial distortion involved. For example, if you follow the outside curve of the ramp you’ll discover that it becomes the inner curve and then switches back to the outer curve. On 10′-wide ramp like this one the distortion is largely irrelevant (it can be corrected by taking a single diagonal move at each inversion point), but as your ramps get wider the distortion will become more pronounced.
But since I’m not modeling racecars seeking the inner track, I’m not too concerned.
More problematic would be creatures flying up or down through the space in the center of the helix. For this, you’ll want to calculate the vertical drop between each half-circle. (For example, on the map above with a 1:4 ratio of descent it would be 10′. Now you know that if the creature flies up 10′, you can move them into the identical position in the next half-circle.)
Nice idea. One, little thing. There is not point B.
Interesting, but I suspect it’s too mathy to be used. Perhaps just have a series of donuts drawn, each one representing one “floor” of the spiral, with a start/finish line drawn through (say) the bottom or top of each one? When you hit the start/finish line, you’ve a/de -scended to the next level up or down, depending on the direction you hit it from.
Now you post this! I just ran a battle on a giant spiral two weeks ago – The Grand Spiral is the main thoroughfare for the abandoned dwarven city that forms the core of my megadungeon. The issue of creatures in the center was key as well – the party was ambushed by a group of gargoyles. Fortunately, once the gargoyles closed with the party there wasn’t a lot of large-scale movement to worry about, but if I had had the tools I might have encouraged it more. Thanks – I’m sure this will come in handy next time!
This gets me wondering if there are toys in the market that are like “builder sets” (think Lego) that we financially-challenged gamers can use for our RPG sessions. 🙂
And Justin, you’re a big fan of Rappan Athuk, right? Did you see this?
http://www.talesofthefroggod.com/index.php/news
Not that I’m aware of any game system explicitly models this, but castle stairs are twisted so that an attacker fighting up the stairs has his sword jammed up against the central column.
With this mapping scheme, the twist swaps every half-turn.
But with that in mind, it’s probably enough to just keep track of who’s on the lower side, and give them a penalty to hit.
Goodman Games’ The Secret of Smuggler’s Cove had an 80 foot lighthouse with a spiral staircase around the outside and an allip in the middle. The map was just a circle, I think I used height markers. The allip hypnotized the party to climb the stairs, took AoOs while they pushed past each other, and got one PC so low in wisdom she immediately left the lighthouse to go skinny dipping. ‘Twas fun.
Fireballs would get tricky on this mapping scheme… but it’s a definite improvement over the standard lack of ability to use spiral stairs. Good stuff.
I agree with Confanity and was going to make the same suggestion. It’ll take up about half the space, too (you’re paying the full diameter ‘vertically’ in your example, and unfolding the staircase like that means each full turn takes two diameters of ‘width’).
Unlike your model, you might have ‘adjacent’ figures not physically next to each other in the model, but you keep the turns consistent and your ‘inner’ and ‘outer’ radii are always the same.
Great post! Thanks especially for the video link. My players have been a bit uninspired with their combat recently, so with this post, not only did I get a good design idea, I got a good inspirational link to share with my guys. \o/
@Confanity/Keith: I’ve tried the “donut” approach on several occasions. I’ve found it tends to result in the players being very confused about who they can actually reach in melee.
The donut approach also makes it a lot more difficult to calculate accurate ranges.
With that being said, this is an Untested post. Wouldn’t surprise me if this method has unexpected problems in actual play. And maybe the spatial distortion will be more annoying than I’m anticipating.
y’know, as an occasional Alexandrian reader I find it hilariously fitting that I came to check some back entries today of all days. That’s because I just ran a session today that had a helical structure fight scene inspired by this /exact/ tony jaa scene.
I used the donut method described by Confanity. It was rather easy to do because the system my group is using is world of darkness and most of the combat is pretty basic roll offs. Obviously the donut hole in the middle became a bigger and bigger hazard the higher the group ascended, and there were some tense grapples that occurred on the edge of the railing.
One interesting feature was the threat of attack from above as well as below, and the increased threat of ranged attacks coming from any direction. Also the PC’s were able to lay ongoing ambushes, as they had seeded themselves into the structure among its patrons prior to bringing out the fisticuffs, and thereby could shed their ‘patron’ persona as the fighting moved closer to them and join the fight from unexpected angles (less applicable for a straight up us vs. them type of engagement or dungeon encounter).
For the inevitable “PC falls down the donut hole” scenario I had allotted a freak chance to grab on to some kind of hanging decoration not unlike the ones visible in the scene, for a scenario somewhat akin to Alan Grant and the other characters hanging from the free floating t-rex skeleton at the end of Jurassic Park. As it happened, none of them took the plunge.
Keep up the good work, GM’s everywhere thank you.
Hey Justin, just going through your back catalogue. I noticed this article has a massive empty space in, preceded by a statement, which suggests you’ve lost an image. Are you able to recover it?
I’m not getting a gap. Where are you seeing the space?
It’s between the following:
“Which is too bad, because there’s a lot of cool stuff that can happen on a helix:”
“Awaking from a dream this morning, however, […]”
Having a poke at the html, it looks like there’s supposed to be a YouTube player embedded there?
Fixed! Thanks!