In what year is Assassin's Creed Odyssey primarily set?

Assassin's Creed Odyssey is primarily set in 431 BC.

The game takes place during the Peloponnesian War between Athens and Sparta. Players explore the Greek world as either Alexios or Kassandra, mercenary descendants of Leonidas I of Sparta, with the narrative beginning around the war's early period.

The setting predates the first Assassin's Creed by more than a millennium. Odyssey also uses an earlier name for the Templar-related organization: the Cult of Kosmos, whose members become targets during the story.

The date can be confused with other famous ancient events. Leonidas's stand at Thermopylae occurred in 480 BC, while Julius Caesar was assassinated in 44 BC. Odyssey's main historical setting is specifically 431 BC, the opening year of the Peloponnesian War.