Spine

Traditional 2D animation draws every frame and stores them in a sprite sheet, which eats both memory and artist hours. Spine splits a character into separate images – arm, head, cape – and hangs them on bones. Animation becomes keyframes for bone rotation and position, interpolated at runtime, with support for mesh deformation and inverse kinematics.

Esoteric Software funded the tool through Kickstarter in 2013. The editor is commercial, but its export format is read by official runtimes for Unity, Godot and a long list of frameworks. The result shows up in countless mobile games: smooth motion, few textures, and a certain rubbery quality you can spot from across the room.