Apparently games that were made with [b]Game Maker[/b] are having these problem. It's probably not on our end but we're still looking it up. [b]Try these fixes:[/b] [b](Option 1)[/b] Opting out of the Steam client beta: go to Steam settings > Account > opt out of the beta. [b](Option 2)[/b] (This method won't count playtime and achievements, but it makes the game work) Navigate to your Reigning Cats directory (right click on Reigning Cats in your Steam library > Properties > Local files tab > Browse local files). You should see Reigning Cats.exe and a bunch of files. Delete steam_api.dll and launch the game.