Oh boi, that music is like from a horror movie! The art style is awesome, reminds me of downwell a little, with its narrow color palette. I think that first stage could get a little harder over time, it's kind of hard to lose. You could also add some more types of enemies, like heavy units, which need 2 or 3 "bites" to kill, or light and fast unit, which only have to be step on to destroy. Overall I can see a lot of potential with this game.

Also, a score system would be really nice, right now you can't tell how well you perform.