This was awesome! I loved the visuals and the gameplay loop was pretty fun too. It didn't take too long to get into a rhythm of shooting down threats, mining some coin, doing the sound thingy, then cranking the generator. It reminded me a bit of Iron Lung, and I really liked the sound design.
If I had to give some feedback, it's that I wasn't sure how much power the generator had. I know there was the green light that blinked, but it would be cool if there was some other indication as to how much power there was, so I wasn't mindlessly cranking. Maybe different colors of light for how much power is left? Not knowing exactly how much power there was added to the tension though, so maybe that was a deliberate design decision.
Anyways, excellent work!