Really innovative
Such a step up from the simple tower-defense game. A massive step up. While I don't really find the standard, top-down tower-defense games very enjoyable at all, this is a distinct departure from that. The ability to control some of the damage through your own actions, and not just your "towers", is a real plus. As well as having the ability to upgrade both that part and the strength of your towers, made for a lot of variety of "leveling-up".
I also can't laud you enough for the style of it. The surreal, fantastical look and feel of it. With the glowing silhouettes against black... the choice of towers and their abilities was so original and interesting... I wish there had been more.
On a final note... these being robots and all, it would further diversify the game-play if the character had ranged attacks as well. Like lasers or homing missiles. Might detract somewhat from the simplicity of the style, maybe... all in all an awesome game, and a very new breed indeed.