It’s a requirement for playing Jazztronauts, a mod for Garry’s Mod. Yes, you’ve read that correctly. You have to reinstall a bunch of old Source-engine games and get this weird ass $10 sandbox thing called Garry’s Mod to play Jazztronauts. You’re also going to need to read these instructions to get the game going. It’s worth it.
There are cats, they talk to you, they want you to steal for them. What are you stealing? Stuff, from random Source-engine game levels, like lamps, or tables, or chairs, or headcrabs in levels made for Team Fortress 2. The cats are funny in their conversations, the gameplay systems are normal but the manner in which you’re to carry them out are just so odd.
You’ll fulfill the fetch quests the bar-dwelling cats give you with a a “prop snatcher.” That’s the device the cats, and you, use to summon a Half-Life 2 scientist model in a t-pose with a gravity gun to grab the objects in the world and pull them back to the bar. A very strange machine in the bar converts those objects into money that you can use on upgrades and new tools to better traverse and collect objects in Source-engine levels that absolutely aren’t meant for you to explore outside of the original context of whatever game or mod they came from.
There’s a lot more to Jazztronauts that I wish I hadn’t known about before I tried it out. It’s very strange to play, and fun to explore the worlds that map makers create, with charmingly funny writing, and you can play it cooperatively with friends. Try it out.