I have somewhat different idea for mind-bending platformer.
1) Imagine that some items do block field of view.
For example there is empty room with box on the ground.
Space behind the box is not visible to character.
Now you jump behind this box. Nothing here too.
But now place where you have been before is not
visible to you.
You jump back to the box and ... there is new box there!
Feature - parts of level that are not visible to character can change.
There can be items that make block transparent to
prevent certain things from disappearing...
2) Any 1 block width/height passage can be a portal.
Portal like in Prey. But without any visual hint that
this is portal.
You walk thru narrow passage and other side of this
passage is different room.
But if you jump over this passage - you are in old room again.
By combining this two features you can make
really big one room platformer!
Add to this 'slightly horror atmosphere', like
signs that someone was there a few moments ago,
probably some notes for the player, and it can
be pretty fun game
I'm trying to make a prototype for this,
but stuck with some technical issues...