Honestly, I really don't like your TD. The controls are unnecessarily abstruse - why didn't you just leave it with mouse controls? The camera isn't helping a lot either in that aspect, making it just combersome to play. I've lost track of where the cursor currently is multiple times until I've just given up to try to get around the controls.
It'd probably be quite enjoyable to play with mouse only (like Plants vs. Zombies) and the camera being zoomed out a little more.