Great game, I hope that you make more levels, the game was pretty short and I didnt really get the feeling. If you would like quickly great new levels, then here is a tutorial I wrote last month:https://www.scirra.com/tutorials/585/how-to-make-an-ingame-costume-made-level-editor
The tank movement is good and easily controllable. You could adjust the sounds a bit, they are too loud. Perhaps you could the game more like a RTS battle, based on the new RTS example, your game would be the first RTS game with C2. This could make the game more outstanding, cause there are very many similiar games to compete with.
I hope that you got some good ideas for your game.