The main historical storyline of Assassin’s Creed Odyssey begins in 431 BCE.
That date places the game at the opening of the Peloponnesian War between Athens and Sparta. The player controls Kassandra or Alexios, a mercenary of Spartan descent whose family history becomes central to the adventure.
Odyssey’s world includes much of the Aegean and Greek mainland, with cities, islands, battlefields, and naval routes shaped by the ongoing war. The campaign also uses dialogue choices, branching quests, and multiple possible outcomes.
The date can be confused with 480 BCE, the year associated with the Battle of Thermopylae shown in the game’s opening sequence. That scene is a historical prologue, whereas the main playable storyline begins decades later in 431 BCE.