At first I didn't get the idea, but then once I got it my brain exploded! This is a great puzzle game! I was about to go the whack a mole route myself but couldn't come up to ideas, but I'm glad to see that someone could (and a great idea at that!) The music is absolutely perfect for the game, and the sprites are awesome as well. If I had to critique, I'd say that it's hard to see the three buttons as they're on the machine (I know you had rendering problems, but because it looks so natural for them to be there I assume thats the intended location.), so maybe make the contrast of the button color and background color larger! Great game overall!
I'd appreciate it if you checked out my game, Donut Wholes, as well!