Which Assassin's Creed game introduced the franchise's first major ancient Greek setting?

Assassin's Creed Odyssey introduced the franchise's first major ancient Greek setting.

Released in 2018, Odyssey takes place in the fifth century BCE during the Peloponnesian War between Athens and Sparta. Its large open world includes mainland Greece and numerous islands, and the game incorporates figures and events from classical Greek history.

Players choose either Kassandra or Alexios as the main character, although Kassandra is the canonical protagonist in the game's wider continuity. The story includes dialogue choices, branching outcomes, naval travel, and role-playing systems that make it structurally different from earlier entries.

Odyssey follows Assassin's Creed Origins chronologically, but it is set several centuries earlier. It does not depict the historical Assassin Brotherhood in its later form; instead, it explores an earlier period and the lineage of the Isu-related artifacts central to the franchise.