Which Assassin's Creed game introduced the Animus concept and Desmond Miles?

Assassin's Creed introduced the Animus concept and Desmond Miles.

The original Assassin's Creed, released in 2007, opens with Desmond Miles being held by Abstergo Industries. Scientists use the Animus, a machine that allows a person to relive ancestral memories, to access Desmond's connection to Altaïr Ibn-La'Ahad. This framework links the modern-day plot to the historical adventures of the series.

The Animus is presented as a fictional technology rather than a time machine. Desmond experiences memories from Altaïr's perspective, but the story distinguishes reliving the past from physically traveling through time. Abstergo uses the process to search for information connected to powerful artifacts and historical events.

Assassin's Creed II expands the idea with Ezio's memories, but it does not originate the concept. Brotherhood and later entries continue to use Animus technology with different modern-day characters and interfaces. Origins, Odyssey, and Valhalla take place earlier in history but were released much later.