I enjoyed the game’s gimmick a lot! I think the character switching was cool, and there were some neat puzzles. I was really impressed with the 3D cutscene and animations too, it was entertaining. RIP to that grem at the start.
I appreciate there not being a big risk with getting hit because of no health bar, but the attacks felt slow and the slowdown hit effect when you get hit makes things drag out more than they should (though maybe it’s partly the framerate issues too?). The final room in the second level especially felt egregious with how many jailbirds you had to beat, and it’s even slower because they can combo hit you and slow things down immensely.
Minor comment but I noticed you could jump after being hit off the ground, related to the coyote time that normally exists. I don’t know if that was intended but it did save me several times.
The lack of SFX and VFX also did end up affecting me. It made the hits feel even less impactful, and sounds for some level occurences would have helped me feel a bit less lost. For example, sounds from interacting with the crystal keys or the final stage book (spawning them, placing them, the event that triggers after them) would have been nice to get player feedback from. Even an animation or cutscene for those would be useful too, though I understand if you might not want to point to those changes as directly.
I had fun overall though! If you continue adding to the game later on, I would love to see what you come up with!