Thread on an interesting new (still in development) way of building Doom maps: https://www.doomworld.com/forum/topic/103999-announcing-bsp2doom-build-doom-levels-with-a-quake-editor
Fascinating! The most interesting virtual world hangout space I have encountered (there is a lot I haven't seen tho) is a minecraft server called nerd.nu. It has been through 23 revs which are when the world is saved and then wiped and everyone starts fresh on a new world. There isn't any fast travel so it is fascinating to watch cities and rail networks/nether roads connecting them grow. It really has an identity as a place unlike most online spaces.
One of my favorite parts is there are cities that keep rising out of the landscape every rev (new world) and have this history and dare I say soul because people keep coming back and rebuilding new versions (sometimes in wildly different themes but still). Every year or so when I get back into minecraft a little I can log on grab a minecart and ride the rail networks visiting the current world's version of rose city or pico city or any number of others. It is cool.