Really nice. I had a similar idea for my game, but did something completely different then :D You fit the theme of the jam really good. The game IS fun, but can get a bit repetetive. For my personal taste, the fun of smashing the block fades way before getting the sword. If you feel the same you might want to tune down the time you need to achieve the sword.
Also the game could be easily & greatly improved by adding a simple counter of how many hits a player already did.
But these are just some thoughts. It IS a cool game, has a well developed theme/story, nice & rewarding audio. It's greatly polished & I love the fact that the broken hammers keep lying around.