Which Assassin's Creed game introduced the Animus as a virtual-reality machine?

The original Assassin's Creed introduced the Animus as a virtual-reality machine.

In the 2007 game, modern-day character Desmond Miles is forced to use the Animus by Abstergo Industries. The device allows him to experience genetic memories inherited from his ancestor Altaïr Ibn-La'Ahad, whose life unfolds during the Third Crusade.

The Animus is not simply a time machine. It reconstructs ancestral memories from genetic information, enabling the player to explore historical events while the modern storyline continues outside the simulation. Later games expand the technology and introduce new Animus users.

Abstergo presents the device as a research tool, but the company is secretly linked to the Templars. This modern conflict gives the series a second narrative layer and explains why historical adventures are framed by contemporary scenes.