Really digging the art style and music! I had a hard time getting through the start of lvl 1. I feel like the recoil of the gun to make you jump high could be increased a lot.
Out of the few times I restarted, there was not a decent block that spawned that I could reach with the gun jump.
Also, I would maybe start the timer of the hand spawning after a certain height is reached, it doesn't have to be very far from the start. That way new players can get acquainted with the controls and make some progress before that threat is introduced.
Great idea, I think you could certainly keep building upon this since I can see the vision. Awesome job!