12 reputable indie game developers have teamed up to make the free dozen chapter curio Experiment 12.
As outlined on creator Terry Cavanagh's blog, the rules were simple: each developer was given three days to make their chapter in the saga. When they were done, they'd pass it off to the next person in the chain who would continue the story.
The exhaustive cast of developers includes (in chronological order): Terry Cavanagh (VVVVVV, Super Hexagon), Ian Snyder (Captain Dan v. Zombie Plan), Jack King-Spooner (Blues for Mittavinda), Zaratustra (Eversion), Richard Perrin (Kairo), Michael Brough (Helix), Robert Yang (Zobeide), Alan Hazelden (These Robotic Hearts of Mine), Benn Powell (RGB), Jake Clover (Not August), Micheal "TheBlackMask" Lawrence (Dopterra), and Jasper Byrne (Lone Survivor).
Having only played the first three chapters so far all I can say is that it's weird. Very weird. It's almost as if you pulled a dozen of the most esoteric game developers from all over the world together and asked them to make a game. Oh wait. That's exactly what happened.
It's a good sort of weird, though. The overall theme seems to be about mental illness, I think, and each creator's chillingly abstract take on losing one's mind is properly unsettling. I was particularly fond of Snyder's hypnotic manic vision of an endless jungle of pastel trees. I won't say any more though, for fear of ruining the dozen devs' mad exercise.
Give Experiment 12 a go at its cryptic Geocities homepage. It's PC-only at the moment, but Cavanagh said "there should be a Mac version soonish."