Rain World is a videogame where to progress you must reach certain places in a specific order. The game doesn't precisely indicate where they are and in what order they must be reached. But Rain World is about the journey, not the destination.
This is why the devs decided to make the destination really good, and the journey as awful as possible.

"Experiment with everything you find in the environment" is a tip from a community guide^ I found. It’s interesting how the fans of this game feel this way while the game itself has another opinion entirely. There’s a yellow guy who follows you showing different icons, leading you in a somewhat right direction: the closest thing to a guide the game has the courtesy of gifting you. There is a specific action that triggers him to disappear irreversibly for the rest of the game.
"Don't be afraid to experiment" is another tip. To be fair there are instances where you're rewarded for experimenting with very specific actions in very specific situations, but they're surrounded by a constant pavlovian reminder that you'll be punished for trying anything except slowly backing away from any kind of obstacle. The randomness of everything in the service of “realism” means that even doing the right thing may yield no result.
"Explore everywhere" is another tip. There exist rooms where you could get stuck with no way out, by the way. There was a gross underestimation of how much RNG enemy placement would affect strategy, level design, and exploration. I’ve never seen such a herculean attempt to make every new encounter with an enemy your least favorite one. Patience is key, but if you don’t find shelter before the time limit you die. You don’t have access to other areas if you don’t survive enough cycles – more of a punishment for dying than a reward for surviving. These elements wouldn’t be a problem on their own, but combined they constrain you to such a repetitive loop of deaths that makes it boring if you are going in the right direction, god forbid you end up on the wrong side of the map and have to backtrack all the way. This is the only game in years where I specifically DIDN’T want to explore everywhere.

I’m coming to the end of my second playthrough and I feel sorry to not have been able to play this for the first time without looking up info on the internet, but I'm not sure how you're supposed to enjoy this blind. I was so dumbfounded by what I was witnessing during my first run that I had to see what the community thought about it, or if there even was a community for this shit. I found a hilarious FAQ^^ for beginners, which mentions the aforementioned tips. Apparently, the "easy mode" that I chose is not recommended since it’s not particularly easy and prevents you from experiencing some of the lore. Its in-game description presents it as “in tune with the mysteries of the world”.
For the record, this game doesn’t expect any kind of crazy tactics, advanced controls, or superhuman reflexes from you. It’s not even trial and error, it’s just unfair: when your deaths have such a heavy RNG impact you learn very little and you can’t prevent them from reoccurring. I don't mean to say that most of my deaths weren't the physiological mistakes I make as a dumb human, but the fair/unfair ratio was unjustifiable regardless of the “statement” the devs wanted to make.
The Reddit guide conveniently compares Rain World to 2001: A Space Odyssey. Although there must be people who see Kubrick's masterpiece as a slow, confusing, tedious, repetitive cinematic nightmare, the fact of the matter is that it was made by an auteur who was able to express his ideas thanks to his medium of choice and not despite it. There are infinite ways to effectively express cruelty in a videogame without being cruel towards the player, I think this is common sense in the arts and entertainment but some reviews I’ve read actually consider Rain World approach as a novel and stimulating idea.
This game wants to tell the story of a harmless little critter, lost in an alien and hostile world, stuck in a perpetual cycle of death. The most effective way to do so, according to the devs, is to make the user experience of interacting with this story as close as diegetically possible to the fictional life of the avatar. You're supposed to feel like that little Slugcat constantly dying and being reborn. You're supposed to feel like an animal in danger. An animal that can’t hold more than one rock in each hand. Or you’re supposed to feel like a person controlling an animal in a complacently irksome game…? That’s how I mostly felt. Are you supposed to feel like the Slugcat can open a menu and pause time? Do you think I'm being purposefully obtuse to make an overly literal interpretation of the game mechanics, and that is a dumb way to discuss them which doesn’t solve anything? THAT IS MY POINT EXACTLY.
Why do I have the strenuous burden of translating my terrible experience as an expression of a struggle for survival when the developers couldn't be bothered to come up with a way to let me engage with their idea without intrinsically compromising the way I'm supposed to engage with it?
I do believe the best thing that can happen to the video game industry is for game developers to try to express their unique vision without compromise. It is good that they tried that with Rain World. I appreciate the attempt more than the result. I’m disappointed because the gameplay is sometimes close to being both unconventional AND good, you can see that it wasn't just left unattended in favor of the aRtIsTiC vIsIoN but a lot of effort was put into it.

Alright, let's talk about the good part: everything that doesn't have to do with interacting with the world. I think this game has the best pixel art ever. The environment design is top-notch and endlessly inventive, and I can't stress enough: this game is about a post-apocalyptic world, one of the most overdone themes in media, and it's so, fucking, nice. Every single area has its own silently eloquent mood, every corner is full to the brim with little details. There's a liminal aesthetic climax after another. The creature design is crazy, some are disgusting, others are distressing, all of them are unique. The procedural animations do a perfect job of giving idiosyncratic life to these designs. The visuals are complimented by a fantastic sound design, from the droning inscrutable machines to the grotesque wet sounds that make you wonder what monster is lurking outside your view.
Unlike the visuals and sfx which can be taken in instantly, I am ambivalent about the soundtrack. If you listen to it on Spotify, it’s an exhilarating electronic juxtaposition of wild and industrial. In-game, sometimes a track will randomly play, and different tracks will layer on each other depending on the circumstances, but the magic of the moment will inevitably be interrupted by death. The game never let me get to the saxophone part in “Kayava”. I rest my case.
Certain scenes Rain World is able to enact are so impactful, a mix of sublime and hopeless that few other works have expressed this intensely. And the organic way they ease in during regular gameplay is exemplary. I wonder why the best moments are the ones where nothing is actively trying to kill you. ("You had to suffer first to enjoy the quiet parts!" - hahaha, no.)

TL;DR: this is one of the best games ever made and I fucking hate it, I wish I could rate it 5 stars, but its imperfections aren't subtle, they get screamed in your face for the entirety of your playthrough.

^https://imgur.com/taS4Cer
^^https://www.reddit.com/r/rainworld/comments/ba8mbm/rainworld_spoilerfree_faq_what_is_rain_world/