Donjon (2002)

From the text:

Donjon is a rip-roaring, make-it-up-as-you-go-along game of bashing down doors, exploring dark dungeons (or donjons, as we like to call them), killing monsters, finding loot, and saving the day. It’s a fantasy role-playing game because you, the player, play the part of a fictional character in a fantastic world. (You get to play lots of characters if you’re the GM.) The best analogy for this is given by Ron Edwards, a bad-ass of a game designer. He likens playing a role-playing game to being in a band: the members get together and decide what kind of music they want to play, one person (the GM) leads off, and the rest of the members add what they have to make something that is, hopefully, exactly what they wanted. Just like with playing music, one member of the band might find a cool riff that no one was expecting, and everyone else jumps on it. Donjon is like acid jam-rock. It’s made to give players a lot of control: they can bust into guitar and drum solos whenever they wish. If something sounds groovy, then they can go with it. There’s no band-leader here to bust your chops.