So... what, aside from trial and error (and this less than pleased review), tells the player that they have to use D to shoot to the left, and F to shoot to the right? Because my first instinct would've been to use the WASD keys for movement and jumping, not the arrow keys and Space.

Aside from that, the five-second "music" loop and the constant firing sound when holding D or F is incredibly grating on the nerves... also, I assume it's a glitch that not only do light taps make the bullets move slowly, but firing in the opposite direction makes other independent bullets change direction.