Love the concept. When I heard the theme, one of the things I thought of was using a tank and shooting backwards in GTA to gain incredible amount of speed, but I wasn't sure how you could make that into a game, and here, you did just that.
I think it might've helped for players to acclimate to the unusual controls by introducing them one at a time. There's a lot going on at first, and while following the text on the ground is very helpful, I foolishly messed with the controls before even realizing A went straight, so I was just bumbling around in the corner for a while. And like some others said below, checkpoints would be nice.