I really liked the aesthetics of the game, it's really cute and well-drawn! The elevated platform where the hammer hits also provides a good visual indicator for where you should hit the packages.
That said, I think the hitboxes of the packages could be increased slightly.
I also found a game-breaking bug. If you spam space, your hammer will be completely broken, and will hit twice from then on. An exploit is if you hit the hammer to change colour, you can actually hit space again to hit the package.
For example, you hit a yellow package with a pink hammer, but in that moment when the hammer is still down, you can hit space again to hit the yellow package correctly.
There is also a delay with the hammer landing, though there is also input delay with my game, so this might just be a Unity thing. If it was intentional, the delay is too long for a game that requires precise inputs.
All in all, I do like the game, but struggled with the delay and encountered some bugs. I do like the gameplay though, and think it can be quite challenging!