Pico8! Nice one. Old school arcade vibes. I found that it was the Z key that fired and not the X as in your submission description. I worked it out after dying once or twice.
Take a look at my game if you have the time. It is a wee strategy game that involves rolling, dragging and using dice to fix space station systems and complete missions.
Houston... we have a problem... https://itch.io/jam/brackeys-13/rate/3343004