The almost monochromatic color scheme reminds me of playing games on my GameBoy. Controls work well, though I felt a bit awkward using the z,x, and c buttons. Would be nice to be able to change the key mapping to a,s and d instead so that my wrist can rest on my keyboard shelf's pad.
Loved the music and sound effects! The graphics have a good look to them once I got used to the color scheme. Gaining some sort of extra poweful weapon (limited use, of course) would have been nice before reaching the boss. I felt my ship was a bit underpowered for taking on the boss as I couldn't tell that I was making any dent in it.
A very good start on this game!