Which Assassin's Creed game introduced the ancient Greek setting and selectable protagonists Kassandra and Alexios?

Assassin's Creed Odyssey introduced the ancient Greek setting and selectable protagonists Kassandra and Alexios.

Released in 2018, Odyssey is set during the Peloponnesian War in the fifth century BCE. At the beginning, players choose either Kassandra or Alexios as the main character; the other becomes a major story character. The game follows the chosen Spartan mercenary across Greece, the Aegean islands, and surrounding regions.

Odyssey expands the role-playing structure introduced in Origins with dialogue choices, branching quests, naval travel, and multiple possible outcomes. It is set several centuries before Origins, which takes place in Ptolemaic Egypt. Although Odyssey features the series' recurring conflict and First Civilization mythology, its playable hero is not yet a member of the later Assassin Brotherhood. Kassandra is also central to the wider canon, but the game allows players to choose Alexios instead.