The easiest way to describe Rain World is as a new kind of survival game. There’s no crafting or base-building or whatever. Each and every one of the game’s mechanics are based around the one real goal you have; stay alive.
You’re a small, squishy little slugcat. You’re not muscley, but you’re quick and clever. You need to gather food so you can hybernate and avoid the planet’s nightly rains, and you need to avoid and trick the aggressive fauna the planet’s littered with. To that end, movement is super important in Rain World. There’s a lot of really smooth platforming, and you have a pretty decent range of motion that you’ll learn the limits of as you practice, sometimes even pushing them. It definitely feels weird at first, but once you get the hang of how it works you’ll really appreciate the way it works.