I couldn't really tell if there was more to the game than just goomba-stomping aliens, and I couldn't figure out how to use the knives once I crafted them. The execution of the theme could have been better, as the aliens could have been replaced with virtually anything and nothing would have changed. Zombies, robots, you name it. Of course, this game definitely has potential with more varied gameplay and more interesting applications of the theme. Keep up the good work!