Which Assassin's Creed game introduced the modern parkour movement system known as freerunning?

The original Assassin's Creed introduced the series' recognizable freerunning movement system.

Its parkour lets Altaïr climb buildings, cross rooftops, leap between platforms, and move through cities using a simplified control scheme. The design made vertical exploration central to navigation and helped distinguish the franchise from other historical action games.

Later entries expanded the system with new animations, climbing options, and specialized abilities. Assassin's Creed II, for example, added more movement possibilities and introduced the climbing assistance of Leonardo da Vinci's equipment in parts of the story. “Freerunning” can describe the broader movement style, while the games also use terms such as parkour and free-running in discussions of their traversal mechanics.