I see a zombie animation on the page, but don't recall zombies popping up. I guess that didn't make it to build? Using punk music to motivate a whack-a-mole game that didn't seem to match the tempo of the music was very unsettling, and likely downright unacceptable to those that do not like punk music. Did you have multiple tracks you could cycle/randomize through to enhance replayability?
Once I understood the timing of the closing circles, I was able to keep up, mostly, but my whacking of the moles didn't seem to produce any results, so I swiftly lost interest. Cute title logo, and the hammers were fun. Adding physics-based hands/hammers (to keep the hammer head flat) and haptics upon a proper whackin' might help the sensation of the game, as its entirely about rewarding timely downward strikes, right? Cheers!