Have you ever read one of those "Haunted game" Creepypastas, that really left a sense of fear and dread in your throat, yet you wanted more?
Yeah... this is the equivilent of one of those.
The gams starts almost cringingly generic, with a bright and cheerful artstyle that looks like one of those bad Mario mobile game clones.
Oh how you will wish you stayed with that happy cute-sy world.
In short, you "evert" between worlds when you pass certain spots in the level. These spots take you to one-off your current world (world 1 you can evert to world 2, world 4 can evert to 3 and 5, etc.). These worlds have different rules, such as scenic clouds becoming platforms and trees becoming dead shrubs. The real notable difference though is the environment. Each world is like a literal decent into hell, and each new world you enter will make you wish you were back in the last.
The game as a whole is very short, but has such an impact that you will remember this game more than any other game you'll play in a long time.