Really cool! It's such a simple mechanic, but very clever. This is an excellent example of how constraining the player can make for interesting gameplay.
The 90% requirement might be a tad high though (or I'm just really bad at this game!). Like some others below, I couldn't get past the straw hat. Got something like 86% with my best attempt.
Otherwise, I don't have much to add. A fantastic job on the art, music, and gameplay fronts. Well done!