I really love how the GameBoy controls are displayed on the screen, and that they actually respond according to which keys you press. I take it this game only has the mouse for a shoot key? There weren't any instructions present anywhere, but this was a pretty basic game to get a grasp of.
The controls seemed to respond well; the gameplay itself is basic but engaging for a short time. The music is also really good, and I didn't find the sound effects to be grating at all. If anything, the only thing missing from the game is expansion. A score system, maybe, different types of enemies and weaponry, because you definitely have a good start here for what was done within the scope of the jam.