Super fun game! I really like how the exchange theme was interpreted, though in terms of the mechanic itself I definitely would have preferred some sort of warning for it, as no warning often took me totally out of the flow of combat.
There were some bosses I really liked and some I really didn't -- for example, bosses with lots of platforming -- e.g. the staircase boss with the weak point at the top -- were somewhat tedious to fight against as getting hit by anything would hit you completely off and basically reset your progress. That being said, other bosses, such as the bird boss, I had a lot of fun fighting against as it felt they were more of a challenge than a task.
Other than that, the game feel is done really well here. The platforming is definitely a highlight of the game, and running and jumping and dashing around just feels really good. The combat is fun and engaging, and the platforming is super fun.
Amazing job!