Chaos is just a weird world. It's probably not practical for survival games, but who knows?
In the same vein as Multi dimensions (though not compatible with it), Chaos is a separate "dimension" which actually occurs high in the air (5000 meters, by default). You can teleport there with the teleport command. I'm still trying to work out how to make a portal that won't drop you in the water.
This is an artwork in progress.
Screenshots
Code: LGPL2, textures: CC-BY-SA and CC0
Mod dependencies: default, bucket, flowers, stairs
Download: https://github.com/duane-r/chaos/archive/master.zip