The idea of making a game simulating a whack-a-mole machine is very cool, the hammer mechanics are completely smooth and their combination with the animations made the game even better.
The art style is simple but fits perfectly.
The difficulty progression is well balanced, while you keep whacking those moles the game keeps getting harder and harder, which is very cool. To make it even better maybe a sensitivity slider would be a great addition.
The sounds are great, but some of them need a little volume adjustment.
Overall it is a very fun and well executed game! Well done!!