Nice! a fun little game indeed.
I wish there was more to this game, because this type of thing cant stay fun forever. But i really had fun while i played it. It was somewhat addicting as it had the elements necessary for addictive gameplay.
I really like the graphics. All the enemies seemed well though out and obviously different from one another. Backround was simple yet very nice to look at. I was impressed by the detail in everything. This game has a great addiciting style to it. It wasnt a breeze either, there were definitely some challeging moments. I liked the idea of being able to upgrade so much, such as the firing speed. Good sound but i think there could be more to it. Perhaps different sound effects when the weapon was changed(sorry if i missed them). The bullets sounded cool and i liked the reaload sound quite a bit. Good audio qualityu topped everything off well.
Interactivity is usually essential in games, and this had enough of it.
Overall a fun gaming experience. I wouldnt say this reached its full potential though. Anyways everything was done well and this is deserving of at least a 4/5!