I've just tested the Linux version. Quite a fun game! The only issue I ran into was that it kind of locked me out of my system when I pressed the Fullscreen toggle. I had to switch to another virtual terminal and force-kill the game to recover.
I had tried to press a lot of keys, but both keyboard and mouse clicks seem blocked. I just tried ESC and it does nothing. Also the rendering stops. But Ctrl+Alt+2 still works so you can login and "pkill -9 KeyCars.x86". I'm using Xfce.
