Any of the Grid games (The first two I don't consider sims, but they are good fun).
N++ (minimalist platformer with awesome physics)
Bit Blaster XL (Simple asteriodish style shoot em up)
So, it seems I mainly only play fun and simple games when I am not racing.
Interesting poll. I see a lot of flight sim enthusiasts, which is cool. I guess once you're into any type of simulator it stays with you forever. I started with the SubLogic Flight sim and also the MicroProse stuff. Amazing that the passion is still with me after all these years.
Insurgency. I've got all the battlefields and many and other fps's but always return to the one that's less than a 1/4 price of just a vanilla BF game. It's no looker, but the gameplay will just have you going back for more, over and over. Can't wait for Sandstorm on unreal engine.
Battlefield series, Mass Effect series, sometimes Arma series and...well I have 2 steam accounts, one for casual games, one for fps and driving (even flight)...I said series?
When I'm not sim racing I like to play Gran Turismo, Dirt Rally and Real Racing 3 on the iPhone, I also like Grand Theft Auto both V and San Andreas, also recently played INSIDE on PC fantastic game