I don't need another hedgehog launcher game with less stuff to do. One was enough. In fact, this is probably a complete clone of another rocket game, except with less depth.
I really like how you made it so that towers can only be placed on certain terrains: It really forces you to vary your types, which involves more strategy. Varying prices as well help with this.
paying for features that seem like they should be standard in a game like this seems kinda dumb... if you arnt using your own engine, than you shouldnt have to charge money