This the Omni dungeon, a super massive dungeon floating in space, created by the madgoddess Grenja.

Each cube is about the size of our moon, if not a little bigger, and it's always twisting and turning, it resembles a rubix cube.
Within each cube is more cubes with massive rooms, twisting and turning, and even smaller rooms shifting about within that, things like enemies (often some variety of undead, being adventurers who failed, or monsters of Grenjas creation such as mimics and doppelgangers), randomized loot, obstacles, puzzles, and you will never know what the next room you enter may look like, and you also may find fellow adventurers you come across may serve as foes as well, be it they lost their mind in the dungeon, or they are driven by greed.

Every other room will have a return pad. Which warps you back to the main hub (the massive entrance) where people have set up pubs and market stalls, and other things like that.

It's very easy to succumb to madness in the dungeons, not only to its sometimes isolating and disorientating nature, but also because some rooms may be affected by the warping or the tarnishing (same thing in different forms), which is a concentrated form of madness that warps people into monsters based of their flaws and traumas if they are unfortunate enough to lose their mind while in these areas.