The music is a bit repetitive, but there's no mute button. You also have some console errors that are slowing down the game. To the other commenters, no one has IP rights for single-colored circles and squares ;)
Did you even test this game before uploading it? The ammo count is always 50 even though it starts less than that. The ammo upgrade doesn't seem to work. The first time I entered the first level I instantly died. I'm also not sure why you thought it was a good idea to use Q as the fire key. Try X.
That level with the one-space gaps is really annoying, and the flash player crashed on one of the triangles in the beginning of that level. Why use a triangle for the player though? I think a square or circle would work better.