With the release of Rain World’s new Watcher campaign, there is a lot to discuss about it and it’s new endings. Rain World is a game on Steam, Xbox, PlayStation, and Nintendo Switch that was made by Akupara Games and Videocult. The base game for Rain World is $24.99 and the Watcher campaign is $14.99 yet it’s only on Steam as of right now.
With the campaign’s release brings back an old slugcat by the name of Nightcat, now rebranded as the Watcher. In their campaign, you get to witness the nature around you without really worrying about ascension because it’s not there—unless you wish to see in the eyes of an echo by the end.

With the “ascension” ending I see it more of looking in the eyes of the Ancients prior to ascension being found, particularly focusing on a young ancient. After you get dragged off by a rotted void worm, you wake up in a bedroom. There’s a toybox, and a cutscene plays showing Watcher viewing and messing with the toys. After that, you can re-enter the save and mess around with the toys yet nothing else has been found with that.
Up next is the rot ending, which holds far more symbolism and meaning to it. In the rot ending, you have to spread the rot through the worlds you as the Watcher go into through portals. Each portal you connect to a rotten region will slowly infect it as well. Once you’ve rotten enough areas, you will wake up an iterator-like being who has been dubbed as “The Prince”. He will tell you to keep spreading the rot, and if you do, it will trigger a cutscene. The Prince will raise his head, and in the white center a karma flower will emerge. With that, karma flowers will blossom rapidly amongst the rot, leaving the Watcher surrounded by karma flowers.

The rot ending more than likely symbolizes the triple affirmative, which was the rot. The rot came, it wiped everything that had existed, and then when there was nothing left it had died off and left a barren land with only karma flowers to symbolize the mass death. The Triple Affirmative is something mentioned a mass amount in the Rain World lore, especially with the iterators. Five Pebbles himself was looking for the Triple Affirmative, and had ended up creating rot which decayed at his superstructure until it collapsed on Shaded Citadel, the cold from Saint’s campaign shown to have killed the rot before it could kill Five Pebbles. The rot ending also may symbolize how the world was starting anew; with no superintelligence shown to have possibly truly created it in the Watcher campaign, it likely had grown and spread all on its own.
This is not reliable information and is more of a theory, and if you have better theories on it then feel free to spread them. For now though, this is the interpretation of the endings that will be spread here. Rain World has a lot of lore and story in it, so there is much room for interpretation.