I had a good time playing, however there were few things I personally didn't like:
You didn't write controls (I hope it was controlled only with AWSD keys), hitbox (3d-like hitbox) - sometimes it went thru me and didn't hurt me, wave respawning enemies (I would like it more if it didn't), no menu, no way to restart the game when you die.
... but it was fun anyway! Can't wait to see your future games.