Fun, and simple, but could use some improvements.
I like this game, it was pretty fun, so I gave it a 4. In order for me to give you a 5, you should really maybe add some things on to it. Add different types of upgrades, like armor, weapon, max health, etc. Also, a good suggestion is to make more of a variety in the weapons, instead of just changing color, it starts to bore people after a little while. :< But none-the-less, I liked this game, and it was very entertaining.