Endorphin is a dynamic motion synthesis software package developed by NaturalMotion in 2005.
[1] Endorphin can be used to generate computer simulations of large numbers of independent characters interacting with each other and the world according to brief scripts or 'behaviours'.
Unlike Euphoria, also developed by NaturalMotion, Endorphin is not an engine, but a 3D animation tool for Microsoft Windows.
At the heart of the software is an adaptive behaviors module which assigns context-sensitive motions to characters based on their surroundings --- for example, football players could be programmed to automatically tackle when near another player, or a swordsman could swing to attack nearby enemies.
Registered users on Naturalmotion's website can attain a free learning edition of Endorphin, however it lacks the feature to export the animation to popular CAD Software, a feature only available in the full version of the program.