Piratecat's dungeon design: fun with tesseracts!



Regdar bashed open the partially ajar door and peered into the room. "Twenty feet square. Empty. Four doors," he grunted back to Mialee. "Nothing special. Regdar finds it boring."

"Let's go, then." Lidda slipped past the burly fighter and headed into the room, and her companions followed. As the door swung shut behind Jozan, though, everything changed. Doors shifted to the center of walls, trapdoors appeared on ceiling and floor, and piles of dry bones that hadn't previously been there suddenly appeared. Worse, some of those bones lay stuck to the walls and ceiling. . . and the massive two-headed troll that was obviously responsible for them also appeared, standing easily on the ceiling.

"We've just teleported!" shouted Mialee in a fluting voice. "Or plane shifted. I'm not sure."

"Later," growled Regdar as he looked up at the troll just out of his reach. "We have other problems."​

In the recent "what are your favorite classic Dragon articles?" thread started by Erik Mona, I mentioned that I got a tremendous amount of mileage out of the tesseract articles back in Best of Dragon 1. It occurred to me that most folks nowadays don't remember or haven't read these, so I thought I'd explain the idea behind them. The last time I used them, it made for an amazingly fun session.

Tesseracts and hypercubes have all kinds of cool mathematical ramifications that don't matter a darn to your D&D game. Don't worry about them. In the D&D sense, a tesseract is effectively a closed dungeon set as a demiplane. Until it is sealed or the trap triggered, it's just one room. Once the demiplane is sealed, however, the room becomes a sealed plane of eight rooms. Each leads into the next in a never-ending loop, and there is no obvious way out. Even better, each wall and ceiling has its own gravity, making for some fun battles.

So what is it? Picture a square cardboard box. Unfold it, and you have six different 2-D panels that look like this:


Now, what if those panels were 3d instead of 2d? If that were the case, then you'd be looking at a top-down dungeon map instead of an unfolded box. Each "panel" of the unfolded box would be a regular room. In addition, there would be a 7th and an 8th "panel" that would sit above and below panel A. We'll call those G and H, set those aside for a moment, and come back to them in a bit.

A dungeon tesseract is typically entered through a trapped room that seems normal while its entry door is opened. It can be placed into any dungeon, and is typically 10' x 10', 15' x 15', or 20' x 20' (depending on the type of tactical combat you want to have occur; more on this in a minute.) Once all four doors of the room are sealed, however, everyone within it is thrust with no saving throw or SR into the closed demiplane of the tesseract.
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[h4]The Simple Version[/h4]

Mialee sighed. "Every room looks just like the next," she complained. This maze is endless!" The elf rolled her eyes.

"No it isn't," countered Lidda as she looked around her. "We're repeating rooms, Mialee. You can tell by the stuff stuck to the walls. I think there's only six rooms. I just can't figure out how they match up, or how to get out of here."

The tesseract is an "unfolded" 3d box where each door links back to itself. Space doesn't work linearly; you can go out a door to the north and come back through a door from the west. A top-down view would look like this.


The entry room is A, and the rest of the rooms spring into existence when the trap is triggered. If the group went back into B and kept heading west, they would run from B to D, from D to C, and from C back into A where they started. If they then headed north into E and then east, they'd come through the north door into C. Better hope someone has a good direction sense.

The only way out of such a place is through plane shift, similar spells, or a secific item hidden in the dungeon that is designed to allow exit. A typical example might be a special doorknob, a special key, or even a ring that turns a door back into a portal to the real world.

In a simple tesseract, there is normal gravity and the top and bottom rooms G & H (remember them?) are simply ignored. It is best used as a six room closed dungeon that is near-impossible to escape. This can be great fun, because it's possible for an ecosystem to develop in these if there is some source of water (an endless fountain or decanter of endless water) and a food source (frequent new arrivals, fungus, or the like.) In such a setting, the strong will have triumphed over the weak, and any unwary adventurers will have to be careful not to be overmatched by the local predator. Alternatively, perhaps only undead or constructs will exist in such a place, or maybe it is being used as a combination treasure vault and trap.
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[h4]The Complex Version[/h4]

Add in rooms G and H, and things get a lot more interesting. Here's a 3d picture of what the tesseract looks like in such a case. The red dots are doors (or trapdoors) leading from one room into the next. The arrows show which doorways connect to which room.


Mialee glared over at Regdar, who was trying to pick up a coin whose subjective gravity adhered it to the side wall. He seemed utterly fascinated. Then she glanced up from where Lidda danced on the ceiling 15' above her head. "Lidda! Come down here!"

"I'd love to," said Lidda shamelessly, "but I'm not sure how to get on the same relative gravity as you have. I ran through a couple of rooms and climbed a few poles, and look at me!" She threw a stone down at Mialee, but it hung in the air for a second right above the elf's head before tumbling back up towards Lidda. The halfling caught it effortlessly. "To me it looks like you're standing on the ceiling. Weird."

Mialee rubbed her temples with two graceful fingers. She felt a migraine coming on.

in a complex dungeon tesseract, each door is in the exact center of its wall. You'd need some way to reach the entrances that are not easily accessible. In a tesseract with 10' square rooms, you can boost one another. In a larger tesseract, you may have climbing poles in the center of each room.


The red lines are climbing poles; each one ends by a door (six doors in each room.) In such a structure, gravity is completely dependent of how you entered a room.

When you exit through a door, it is ALWAYS as if you climbed up a trapdoor. Thus, in the above diagram, if you were on the floor (normal gravity) of room F and decided to go down through the door in the floor (F6), you would emerge in room H standing on the near wall (H1). Relative gravity would have shifted.

If you were on the "floor" of room C and wanted to get to the ceiling of room C, you would go:
Exit by C4, entering A2
Exit by A5, entering G6
Exit G2, entering C5
Voila! You're on the ceiling of C!

Alternatively, you could simply climb up the pole to G2, turn around and climb back down again. Much easier.

If you didn't want to muck around with variable gravity, you could also decide that gravity was consistent throughout, and didn't vary when going through portals.

I find the complex version fascinating, because 3d combat where some people are standing on the wall and some people are on the ceiling can be a lot of fun. in such a tesseract, room size is very important; for instance, if each wall is 40' square, you can only have ranged combat with people on the ceiling. If it is 10' square, things are a lot more intimate.

[h4]Using tesseracts in a game[/h4]
I originally used one as an "unescapable" trap designed to lure in and trap a NPC's enemies who tried the "scry and teleport" trick. The tesseract had its own ecosystem and series of powerful inhabitants, including a cannibalistic drow and his skeleton "family", a wraith who demanded life-energy in exchange for water and fungus, an insane priest with three followers who used "create food and water" to demand total loyalty, and one room that was commonly agreed to be neutral territory so that the different power factions could meet and talk with one another.

They make good jail cells as well. Powerful churches or wizards may use such things to contain their enemies, one of whom the PCs might be trying to find and save.

I think these are most useful for catching jaded players off guard, and unsettling them with something that isn't immediately intuitive.

Anyways, I think tesseracts are interesting and fun; lord knows that they've sat around in my subconscious for over twenty years. Hope this is of some interest or use to folks. Questions, comments, mistakes?

- Kevin Kulp, Piratecat
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I remember that!

Thanks for bringing it back to the surface for me! :cool:

Is there a way you could edit the pics to get them working? or perhaps that is just something on my end?


First Post
I remember the idea of a tesseract from "A Wrinkle In Time" by Madeline L'Engle; they used it as a means to conduct dimensional and temporal travel by describing time and space as a tesseract... pretty trippy stuff, but cool nonetheless.
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Great this is just the thing I needed to make them really hate the BBEG (and me), now to just come up with an interesting ecology. Thanks Piratecat! :)


Heh! I remember those from Dragon too. Nicely done Piratecat. I might actually have an application somewhere in my game for those this time around.


Are the images visible now? That'll teach me to link my pictures from a closed forum.

All pictures were done in Excel. I love that program. :D

Here's an interesting page on mathematical tesseracts and other 4d shapes.
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First Post
I remember seeing a movie called Hypercube. It wasn't that great a movie, but it might be worth a look for those that are interested in some of the ways it can be used.


First Post
Cube never specifically stated that it was a tesseract, but it might as well have been. In Cube, each room was more or less a death trap; the rooms where all part of a gigantic cube that cycled where each individual room was in relation to the true exit from the total cube. The cube had an astronomical number of rooms (by the participants' calculations), and one needed a degree in advanced algorithms (or had to a be numbers savant) to figure out the cycling time and pattern of the Cube to escape it.

Hypercube... no idea, though.

Cube could make an interesting one-shot dungeon, particularly for a d20 Modern game, as long as the people playing it hadn't seen or heard about the movie. Such a module would mostly be a meat-grinder, though... but it might be fun to DM if all the players knew up front that they were going to die in the most special-effectsy sort of ways possible. :D
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First Post
Cube was a great movie. Haven't seen Hypercube though.

Though I'm sure PKitty could use it to take this tesseract dungeon to whole new levels. :D


Registered User
The movie 'Cube' didn't have a tesseract, it had just a large collection of cube rooms that mechanically moved around, the whole thing formed a cube itself that was within a larger cube, the larger cube was just large enough for a room cube to exist and move around the cube of rooms. There was one extra cube that acted as the bridge between the cube of rooms and the exit door that was on the side of the larger cube, it was only there at the start and end of the cycle of movement, once every few days. a lot of the rooms were trapped.

Cube 2: Hypercube, was a form of a tesseract, and as portrayed in the movie, had an almost infinite number of rooms, the group gets placed within one room and then that room 'unfolds' into an almost infinite number, then it starts to collapse into itself again. Traps were present as well, no numbers to help out though.

I liked Cube, not as much Hypercube.



I have seen both Cube and Hypercube, and although the sequel isn't as good as the the original I can recommend it if you liked the first movie because of the cubes and not because it was different. :)

Anyhow, nice cubes!

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