So charming! Love the little metroid reference, and the music fits the tone of the game perfectly. The end boss(?) also fits well into the tone.The game accomplishes a lot with it's simple, outline style - a style I might have to try out in the future.
It's been said before, but I am curious why you decided to bind movement to the mouse. I'm guessing so that the player didn't need to move their hand when they checked their phone?