What gives the characters of Rain Word their distinct naturalistic movement and expressiveness is that they are created using a blend of classical animation and code-based procedural animation. Unlike traditional sprite-based animation which flips through a few set poses for character actions or movements, Rain World characters consist of freely moving interconnected limbs and body parts each with their own weight and range of movement, etc., just a like a real body! Each limb is then individually animated with a wide variety of actions and motions.
This all means that when a slugcat is, say, climbing up a pole, each limb "knows" its own length and is able to grab/release the pole accordingly, presenting a natural looking hand-over-hand motion. Similarly, when a lizard is crawling along the ground, each leg acts as an individual motor, pulling the lizard the distance of the limb at a certain rate. And more excitingly: when you knock that lizard off-balance with a thrown rock or brick, breaking its grip on the ground, sometimes the weight and momentum of the creature's own long tail will drag the hapless, scrambling beast off of a ledge to its doom. Cool right!
You can see some of this leg and body movement action with the help of our little friend the see-through slugcat. The red markings indicate a specific limb or body articulation. Its almost like a complete skeleton of a slugcat!
