Great use of the 2 button modifier! Also great use of the asset packs you listed to create a cohesive vision. It's a "simple" game in concept, but definitely challenging! (for me, anyway... XD) It's also awesome that you let your son "help" on this.
If you carry the game through to a future round, I'd like to see some difficulty balancing/scaling. I probably just suck at the game, but I did find it hard to ramp up to a flow state where I could consistently dodge bullets. Also, maybe a quicker restart after dying.
Best of luck in the round!