Region Tier List (Base+DLCs)
I know it can be a bit grating seeing these tier lists over all the subreddits but I've never posted one and thought it would be a fun exercise. I'll also briefly go into the placements and categories below:
The "Apex" tier is comprised of the regions I would call the "final exams" of Rain World. These regions test you on your skills with their respective slugcats--swimming and navigation, combat, movement, ecology, and climbing and heat-management, respectively. They succeed in all areas of design and I have very few nitpicks with them.
The next two tiers are regions which succeed at their respective themes and gameplay styles, but simply not to the degree that the Apexes do. Regions near the bottom of "Good" tier may either have minor design issues or simply don't excel enough in any particular area.
I struggled to come up with a suitable name for this tier, but "Half-Baked" comes the closest to how I feel about about them. These regions either have notable design flaws holding them back from succeeding at their theme or feel more like "set-pieces" without enough meaningful gameplay to make them interesting on repeat playthroughs. More depth, breadth or polish would go a long way to improving these areas, in my opinion.
And that's all! That's all the tiers. Nothing else exists. We're done here. OK, there's the rotten regions, but I honestly see those as more of a bonus inclusion or a sort of "fail state" for trying to cheat the system. If these weren't in the game, I wouldn't miss them, but they're inoffensive. All in all, I would say Rain World (in its current state) doesn't have any regions I actively dislike being in, which is kinda insane for a game with this much content in it. Bravo, devs!