Funny, but it has some bug, i put the motorcycle, in horizontal a few times, you coultd either turn it in a game over or limit the rotation of the model(you can use a animation instead)-
Graphically look great, the low poly 3d work well with the color schemes.
The tap it's a little unpredictible, somethimes go to the other side of what i expect, not sure what logic follow.
For the speed it run i add a small i con do idicate the direction it gonna move on tap.