This is really sweet! I really like the flick mechanic. It almost makes it feel like a rhythm game as flicking away to one target and lead right into the next target. I'm wondering if it would be cool to force the player to kill the targets in a certain order where the mouse movements naturally flow into each other. And if you synced it to the music too?? I'm not sure if that's what you had in mind but it could be cool to go in that direction with this.
Really slick. Well done!