The small robot faces huge number of zombies who keep staying on one place and you can destroy them for distance. But you have many things to overcome.
The first and the most important thing to fight with are the zombies. You have to liquidate them all to get into the next level. But other things appear as well, there are mostly walls and then logic riddles as using chain reactions and bouncing. Your shots can have various intensities. The graphics is really nice and the levels design just well made. However, I mostly hope for luck than my skills.