Original gameplay, difficult and very good
My main complaint is that the little worms, which can be used for healing, abound at the beginning of the level (when you don't need them) and later pretty much disappear. It would be nice if either they kept appearing occasionally (although there are other health bonuses later on) or the worm wouldn't eat them when it's at full health.
Another suggestion, can the mouse icon be enlarged? I often lost track of it and even went out of the game screen, which made me lose control.
Except for these issues, gameplay is original and good, there is enough variety of enemies to make it interesting and bonuses to enjoy. A really good game!