It was his 2nd game with Unity and for the iPhone.
There is some cool stuff going on with the physics and the cars have a nice feel to them when playing the game. All the cars, characters, trees and icons are quad planes with billboarding textures that change it’s UV offset to swap different frames. Because the game had to run on older iPhone models as well some extra work went into optimizing the framerate so that the game play is always between 45.0 – 50.0 fps.
Not sure if those were his inspirations some games certainly were but Marks first game of this kind with the same name was developed for flash some years ago:
But that game is no comparison to the unity one as the framerate is really choppy almost capped at 24-28 fps and the physics are not really present. So this is the flash version on youtube: