Right off the bat, love the title screen and logo! The logo is super cool and stylized and I really liked how you blended it with the background!
The music's also really nice, makes me feel like I'm on a mission!
The gameplay is really interesting. Switching between both worlds seamlessly becomes very rewarding once you start to master doing it midair. Trying to get quick shots between worlds to avoid getting hit whilst still maneuvering the character midair was really fun! Kinda made me imagine a speedrun of trying to kill all the enemies and how sick that'd look!
Trying to master the controls meant I was completely cleaning the rooms, which meant I had a lot of materials to use for potion crafting! Needless to say, that boss was liquified.
There was a tiny glitch where a collectable wasn't obtainable or didn't disappear, but other than that, everything was super polished and felt really nice to play. A really strong and solid entry! I'd be interested to see, if there's to be further development, which different ways the between worlds aspect would be applied. There's a lot of interesting possibilities with it.
I enjoyed playing it! It's fun!