I had not heard of this game before, it is a racing sim with real cars and tracks. Looks quite good and has been added to steam early access. Details look good on the cars and tracks and there is an initial selection of both that seem quite good to try out also. Would probably work best with a wheel though...
I highly recommend this game to anyone who wants a awesome racing simulator, this game uses some of the best tire and physics models available.
Their previous simulator Netkar Pro was awesome and had the most realistic driving I had tried yet, I would of played it more but had issues with my serial for the game.
Also this game is supporting the Oculus Rift and does have it already in the game, but it is quite buggy for the moment, but once fixed, will be ridiculously awesome.
Lastly, this simulator is made for a wheel, it may have controller support, but if its like Netkar Pro, the controller feature is just tacked on for the hell of it, but no real time is spent making it work half decent.
Assetto Corsa > All, but iRacing has a good engine as well.