As a game developer and a user on STEEM these kinds of discussions are great. In my opinion STEEM could be used to replace most of the server side "cloud" API's to decentralize things like saved games, high-scores, achievements, etc. So any game could benefit. I'm going to be working on a game for this months Godot Wild Jam which should include some of my proof of concept STEEM Integration. As for what kind of games I would like to see... I think I would echo some of the other responses and say a good racing game or an FPS would be fun.