I can't consider it a game if all the point is to tap two keys.

Needs a lot of improvement.
Depth, storyline, less repetitive, more interactive, etc.

Very repetitive

interesting and addicting concept

I like the pixel graphics and the music. The difficulty curve escalates a bit too quickly, but maybe that's just me.

Like what others said before, you can just push the z and x keys at the same time throughout the whole game. That would be worth fixing.

hard to understand and pointless