Whoa, is this a horizontal top down shooter? Weird. At first I thought it was side view then I saw the tank and it threw me off.
So going on that assumption...
1. Why is the ground a striped pattern? Isn't it some sort of dirt material? In general, everything is kind of hard to read.
2. That tank really needs some more contrast and/or color variation. Right now it doesn't quite match the rest.