The ghost mechanic is clever, it didn't always seem to work perfectly, sometimes I was waiting around and they never seemed to show up and then when they went ahead of me, sometimes they got to the puzzle too quick, even though I tried to make it so they stood on the buttons for ages before killing themselves.
Personally I don't think it needs a tutorial, you get to your first death very quickly (although I don't think I saw a ghost the first time, but on my second death there were 2), I think there might have been a delay in the first one coming out because when the game started the music was so loud I was checking for a volume control then turning my computer volume down. So maybe don't "record" the player until they're out of the door?
Speaking of doors, I think you had to go too far into the door to trigger the next level, the first time I went up to the door and nothing happened so I went away and looked around and then I went and looked at the instructions again and really only triggered it by a fluke.
Several people have mentioned the room with the 3 platforms. I could not solve this one. The button for the platform that goes up to the suicide spot is on the other side of the room so I could not figure out how to activate that while being on it with a different version without being able to kill myself.
I also had a problem with sometimes my jumps not registering, I thought it was that my spacebar has been used and abused testing all these jumping games (and making my own) but someone else mentioned it too when you're near the edge of a platform. If you're using " feet" collider, maybe make it a little wider, give the player a little more leeway/generosity.
I wish I'd been able to solve that room and see the rest of the game. Maybe you need to do a walkthrough video!