A couple of things.
First, the big one: I don't think autofire should be a powerup you have to buy. Not for something like this. I think that autofire should be a starting feature and active by default, and actually require going through a "Are you sure you want to do this?" prompt to turn off. I get you wanted interaction, but you need to account for repetitive motion strain being a thing. At the absolute minimum you need to spell out that it's there, possibly by making it a forced first purchase. But IMO it should be a default option.
Second. the timing needed to score 100 points in one round on King Cobra's "Simon Says" gem is perhaps a bit too tight. I'm frankly surprised I was able to pull it off.
Other than that, the game is fun.