This game is absolutely awesome, terrifying and gorgeous. I'll HIGHLY recommend going in as blind as possible, similarly to games like Outer Wilds. There isn't really a good genre to fit this game into, but if you really need one I'd most describe it as a blend of platformer and metroidvania-of-information, with an incredibly in-depth lore and open-world.

On the platformer side, this game has the most insanely in-depth movement system; completely different from that of any other game I've played, but highly comfortable and adaptable as you begin to learn more and more. Most movement is not taught explicitly, but much can be uncovered, recreated then learnt either in spare moments in-game, or in the highly customisable sandbox/arena mode. There is a great spoiler-free movement guide online to chip away at if you'd like to enhance your gameplay bit by bit. Advanced movement tends to have more like rhythm-based inputs, which is great for muscle memory, more similarly to platform-fighters than platformers. I'd highly recommend keyboard for the ease of precise directional input changes, like in Celeste.

On the metroidvania-of-information side, this game tends to be overwhelming to progress through, lending to flipping between settling down then pushing into the unknown. The game's oppressive world is not designed for a rodent like you, and so its open-world will feel very restrictive at first, containing many road-blocks of creature and item understanding which will come with time via experimentation. The "intended route" comes from a mix of this road-block system, with occasional help from a mysterious creature in-game. As you progress further into the game, you will begin to build up more of an idea of your purpose/role in the story, helping your decision-making and directions. After a first or second playthrough, the scope of the world will feel much more free for comfortable exploration, and you can choose to be put swiftly back in your place by the hard-mode, which adds new creatures, mechanics and some heart-wrenching story-beats. Each of the many revelations about an interaction, behaviour or ability feels incredibly rewarding to figure out, allowing for easier and safer passage through the many environments you face.

As for the lore, it comprises a perfect blend of environmental story-telling with more explicit mysteries and realisations, taking place on a hostile post-apocalyptic alien planet. Don't expect to know much anything about the backstory of the world or anything in it until 20-30 hours into the first playthrough.

In terms of flaws, this game has very few in the long-run, the biggest for me being a slight lack of explanation/tutorial for user interface controls, i.e. the ability to view the map in the menu between cycles, and the system for limited fast-travel.

10/10 fantastic game, though I'd recommend going in with a friend who is good at spoiler-free advice, or using the spoiler-free channels in the Rain World discord server. (Oh and the music and art is stunning)