The main story of Assassin's Creed Odyssey begins in 431 BCE. That year marks the opening of the Peloponnesian War between Athens and Sparta, the large historical conflict surrounding the game's Greek setting.
Players choose between Kassandra and Alexios as the protagonist, while the game's canonical novelization identifies Kassandra as the central hero. The story follows the protagonist across the Aegean world, including mainland Greece and numerous islands, during a period of intense military and political rivalry.
The year 480 BCE belongs to the earlier Greco-Persian Wars, including the Battle of Thermopylae, which appears in the game's opening sequence but is not the beginning of its main story. The Peloponnesian War historically lasted from 431 to 404 BCE. Odyssey was released in 2018 and uses role-playing systems such as dialogue choices, branching quests, and equipment levels.