Pretty neat little game! The music was cool and the art style had a nice cartoony vibe. Blasting through waves of enemies was quite satisfying, although the primary pistols could have used a bit more "oomph" in terms of sound effects. I also wish it was possible to look ahead a bit with the mouse.
The turtle boss was very cool and had some impressive attack patterns, but got stuck in the wall towards the end. Otherwise, the only major issue I had is that I'm not sure stamina and energy bars really count as "side effects." Still, very nice job!