Nice art and music, especially the player sprites. I was confused a bit at first with the walls being the same colour as the ground tiles though. Enemies also have a habit of ambushing from off screen, a sound cue or a visual indiecator would do wonders.

I like the art of the game, but I felt the world was too open and I was just swimming aimlessly. When I did find an enemy it caught me off guard and killed me. Its a cool concept though.