I wish I could give this game a try and properly give some feedback but since it's online co-op only I couldn't at least play with two controllers to test out the puzzles.  You could even make it playable with one player by letting the player switch between each character (if the puzzles are possible to solve this way of course) Or you could try having splitscreen as an option?

This is totally subjective btw but I would not suggest making an online-only multiplayer game unless you already have a huge following because if the game launches with too few people playing then nobody can match up and play. It's possible to do, but I would personally just have a single player mode at least. Good luck with the game's launch!

Oh, the one thing I can say is you should add the ability to skip the game's text intro!