I bought the AVGN Adventures game from within the Valve software on my Mac. After downloading the game using the Valve software, the software said the game was Windows only, so I could not install it.
At the support forum I asked for my money back, since it is ridiculous to sell a game using Mac software and then it will not run. Support refused to return my money.
I complained so many times, the support time cost them more than the actual game cost ($10).
Since the games say what they run on when you buy them, I wouldn't give your blind ass a refund either.