Procedural animation
Motion computed at runtime from rules or physics instead of played back from keyframes — how a lizard's feet find uneven ground no animator ever saw.
Hand-animated clips are fixed: they know nothing about the ground, the slope or the collision in this particular situation. Procedural animation instead computes the pose every frame — inverse kinematics plants feet on steps, a ragdoll falls according to physics, spring bones and Verlet chains let tails and cloth sway, and walk cycles can be synthesised straight from velocity.
The price is control: an animator refines a feeling more easily than a formula does. Games like Rain World and Spore built their whole sense of movement on the technique, usually blended with traditional clips.