Do you know any game which actually uses cryptocurrency? I saw a lot of coins which promise this, but usually It ends up in being scams.
Games are for fun, but It would be more satisfying to have a valuable currency for games.
Cryptokitties, nexium and i heard it has been listed on the steam store. I never heard any other existing platform. In my experience i'm only paying SDK games to tested the blockchain. Honestly to make the crypto will be used in the game looks so difficult because it can be considered as dapps platform.
Just fyi, being listed on Steam only require a listing fee, there is no actual requirement for it. So basically getting listed on steam store isn't something to be proud of.