Jazztronauts is a mod about how mods are made. In this clever meta-modification for Garry's Mod, you (and optionally your pals) go on scavenger hunts through the 15,000+ maps already on the Steam Workshop. You're hunting for glowing crystals while stealing everything else (from chairs to wall textures) to sell for cash to spend on persistent upgrades, then escaping in a wall-smashing cosmic tram car. Jazztronauts is out now, and you'll need Garry's Mod (plus some extras) to play.
This is a surprisingly educational mod. Your home base contains a museum of Source Engine mapping technology and tricks. It teaches you what brushes are and the tricks used to make everything click. And then it equips you with the tools you need to turn everything inside-out, warping through walls into spaces not meant for regular play to grab gems that may have spawned 'out of bounds' and then escaping.
All of this takes place over an incomprehensible number of wildly varied levels, randomly picked from those on the Garry's Mod Steam Workshop. While you can do the whole thing solo, and I'd imagine it's an almost meditative experience played that way, the Jazztronauts team envisioned this as best played with with a group, especially if you've got a collection of silly character models. The higher your team's tech level, the messier it gets.
All of this anarchy is surprisingly structured, too. After a Stanley Parable-inspired intro stage, you'll operate out of of a weird (but classy) interdimensional jazz bar, home to four weird cartoon cats. In-between scavenger hunts, you can talk to them, do quests, earn rewards and even apparently date them. Progression is saved per-server, so you're probably best off playing with friends, but there's nothing stopping you from diving into a public game.
Jazztronauts is out now, although installing it is a little fiddly. Here's an FAQ with details (including some known issues being worked on), but here's the short version:
You'll need Garry's Mod to play, plus ideally Half-Life 2 (and both expansions), Counter-Strike: Source and Team Fortress 2 installed for their assets, unless you're prepared to see a lot of missing textures and ERROR boxes around the multiverse. Got all of those installed? Then hit the Subscribe All button on either the Vanilla or Recommended Workshop mod-pack for the game. The latter includes some handy extra features, and a vuvuzela. Happy larceny!