Personally, I think you'd be better off ditching the player choice for their team at the moment, I tried them all quickly and really didn't see a difference in how they played. Since the enemies went down with one hit of the cane, I just spammed 'A' to kill everything.
Being able to swap the playable character at any time is a neat idea, but I think it needs more polishing to really work. It didn't always seem to switch when I'd hit the buttons, and I couldn't always recall which person I'd be switching. Since the resolution so large, would it be possible to stick a reminder for who's tied to which button somewhere?
The large resolution feels like it's wasted at the moment, since so much of the game is dark outside of the puzzle rooms. I found the visible range to be way too small, since quite a few enemies would spot me before they even entered my sights. The small visibility combined with the slow walking speed made the maps feel like a chore to traverse.
I didn't watch your demo video at first, so I went into the puzzles blind and unfortunately couldn't figure out hidden puzzles 1 & 2 (which may say more about me than the puzzles themselves

). A bit of direction with the puzzles would have be quite useful. I did do the tutorial puzzle, but that one was so simple that I did it with one character. I'm not sure if it was intentional, but the elemental pillars that appeared around the buttons could be pushed out of the way or jumped over, so the other three characters seemed unnecessary. When it came to hidden puzzle 1, I did skip around your video to find it since I was unable to in-game... And it's hidden behind the HUD?! Please don't hide things behind the HUD, maybe some people would realize it was there but I doubt most players would. As for the puzzle itself, I stepped on the button and it went down, which made me think I didn't need to push the boulder onto it (again, it's possible I'm just terrible at puzzles...).
The maps were okay for this type of demo, but there were some trees missing their trunks near paths that went left and right. While most of the enemies turned into their proper downed images when beaten, the spirits seemed to prefer to turn into SWAT people.
There was no menu option to look at my items, so I'm kinda confused as to why I'd get Rare Diamonds from the puzzles. I didn't see an item button listed on the controls either, so it didn't seem like there was a way to check what I had.
I got an error when I quit to the title. It didn't happen every time though, so I'm unsure of the cause. Hopefully the error message is helpful.
Overall, it's possible that other people would enjoy the concept but I think that it currently needs a lot more work and depth.