I liked that shooter game. The button to change weapon is definitely a plus.
Nice minimalistic art. I liked the background color change even if it's just simple dithering.
However, WASD / Arrows weren't listed in the Controls. The boss's HP didn't seem to go down when I attacked it. And sadly, there is no Game Over screen with a Restart feature.
The music was pretty good, but the volume was too low, especially in comparison with the SFX.
Fun little game.