What Hem said, generously giving half a star for crediting the original author plus attempting to create some sort of level demonstrating the key idea, but the level itself is an utter failure and not enough effort was given to understand what exactly that key idea is.
On top of that, if a demonstration was the main goal here, a long hallway that need to be traversed over and over again that serves no purpose is just annoying.
Actually not that simple. Execution is a little bit messy, but it does help obscure the solution. ************************************************************************************************************************************************
Insights