It's too short for the money, I finished it in about 2 hours and can't see much reason to try it on a harder difficulty mode as it will just be more monsters. There are only four types of monster with palette changes: beetles, spiders, aliens, zombies. The monsters teleport in from nowhere and can land right on top of you. The power-ups spawn in response to killings and therefore tend to form chain reactions that suddenly remove any pressure. The music is a short, repetitive loop. Luck is a huge factor: if you only have a pistol, the enemies tend to drop weapons, but once you have a weapon it is much less likely that a different weapon will drop. If your first weapon on a level fires rockets, you win, but if it's the blowtorch or the wave-emitter, you lose. Get Alien Shooter instead, it's free.
