I don't know what happened, but Double Fine updated their game engine and now "The Cave" on Steam looks really weird. The colours are totally wrong. See:
I'm on Arch Linux 64bit, Catalyst 13.4, Radeon HD 6670.
I also experienced that bug with Catalyst 13.4 and 13.6 betas but it seems it has been resolved in Catalyst 13.8 beta. Give it a try and see if it is fixed.
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