Rain World - Aether Ridge

Aether Ridge was made by Kaeporo, you can find it on http://www.raindb.net/

This place is so scary... The platforming reaches a level not previously exploited by the base game, and the region utilizes vanilla mechanics to the most powerful and unique extent it can. The region is much more than just levels!

I've eagerly watched the progress of Aether Ridge and waited in all the time that it took to release, and I have to say I was not disappointed one bit. The levels themselves reach an amount of detail sometimes beyond the vanilla game, and provide a lot of challenge in platforming that had me on edge constantly.
The one thing I did not really like was the amount of inaccessible pipes that tantalized me, though you could just use the vanilla theme of "this world was not made for you" to explain that.

Overall I feel like Aether Ridge had been given many things by vanilla, and chose to forward them in all the ways the base game couldn't have (because of it being too difficult for new players etc).

With there being so many rooms (200!!!!!) I could not get to everywhere in this video, so definitely try out the mod to see it all.