Spine - Spine is 2D animation software designed specifically for software and game development.
Unity - The multiplatform game creation tools for everyone.
Creature - Creature 2D Skeletal and Mesh Animation Tool
Godot Engine - Feature-packed 2D and 3D open source game engine.
Unity 2D - Unity 2D is a powerful and feature-rich game design solution built from the ground up to fulfill every basic and advanced need of the developer.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.