What is the name of the first Assassin's Creed game to feature a fully explorable ancient Greece?

Assassin's Creed Odyssey is the first Assassin's Creed game to feature a fully explorable ancient Greece.

Released in 2018, Odyssey is set during the Peloponnesian War in the fifth century BCE. Its open world spans mainland Greece and numerous Aegean islands, allowing the player to travel between cities, rural regions, and coastal areas. The game includes historical figures and locations while presenting a fictional adventure within that period.

The player chooses between siblings Kassandra and Alexios as the protagonist. Kassandra is the canonical protagonist in the game's official novelization, although the game allows either character to be selected. This choice is separate from the earlier question of which Greek city-state is associated with Kassandra.

Assassin's Creed Origins came first chronologically within the franchise's historical settings and focuses on Ptolemaic Egypt. Valhalla covers Viking-era England and Norway, while Mirage is centered on ninth-century Baghdad.