Baba Is You is an indie puzzle game where you control a cute little rabbit thing in order to move blocks that make sentences which allow you to beat levels; the Xtreme version is the same, except someone slipped something into Baba's drink and now you must do everything while you and the rest of the world slip, slide, and rotate in all the wrong directions.
While this spinoff follows the same rules in terms of what sentences do (thing is thing), the fact that there the tile system for movement was replaced with ice-y floor and rotation physics makes the game difficult not because of the puzzle (all of the puzzles are basically the first world of the original game) but because of the fact that things will move wildly depending on the orientation of the text and of what you're controlling; one moment, you can have Baba completely horizontal, and with a slight bump on anything at all, Baba will now be at a 45 degree angle (or better yet, completely upside down). It's definitely the type of silly game mode that would've been a nice unlockable in the base game, so seeing this become it's own spinoff for others to enjoy is really considerate of the developers.
***SPOILERS***
Even though all levels are beatable with enough patience and trying out different combinations, I have to stress how bad level 7 feels to play because of the established movement; you have to make a rock bridge for a key in order to open a door, but the key will constantly move downwards with a gap being between it and the door. Now, this wouldn't have been such an issue if the rocks you use to make the bridge would reliably hold the key up, but both objects interact with each other in a way that allows the key to slide off the rocks really easily. While I was lucky to have been able to balance the key on a rock, this level felt way more tedious than it should've been because you had to have the objects in just the right spot for the bridge to actually work (by far the most difficult level simply because of this interaction).
***END SPOILERS***
All in all, this was a silly little spinoff from the original series that I neither expected nor realized I would enjoy. Definitely give this a try, but keep in mind you're bound to get mad at the physics while you're getting use to them :D
My playthrough: