If you found this one hard, do not play the prequel hahaha. I'm glad the difficulty didn't throw you off, I was scared it could happen. You're right about the first room, there's just tiles missing off-screen. For the room with the ceiling too close, I'm actually wondering which one you're talking about, perhaps if you could describe it a bit I'd be able to help you! Anyways, many thanks for playing and glad you enjoyed!
Well, it was the one after you avoid collapsing floor by activating the blue platform, then you can detect message, that the floor is not stable. There is no way to jump into next platform. I guess it means i need to turn back (seems like thtere was some things to do in this room with for arrows with letters)