Very good concept and the gameplay seems to be working. It's pretty addictive already actually!

Only critics I have is that the game isn't exactly very good looking and that the concept begs for more options. For example policemen that can set spike-traps to slow cars down or roadblocks and so on. By the time the difficulty has reached a certain point, you'd probably want to give the player those kinds of abilities. Otherwise this game might become repetitive pretty quickly,

Cheers