Great game, graphics are simple and nice it's fun well paced. I's very polished. Just awesome.
But:
Games lags when there are a lot of enemies, try removing dynamic lighting, and adding simple blob shadows. Also maybe its better to use flat shading on objects.
While I have no problem with this games theme, some people might find it less palatable killing cute farm animals. Cute giant bugs might work better, just retexture your models and give 'em extra pair of legs.