What was the first Assassin's Creed game to use a fully explorable open-world Egypt?

Assassin's Creed Origins was the first Assassin's Creed game to use a fully explorable open-world Egypt.

Released in 2017, Origins places Bayek of Siwa in a large version of Ptolemaic Egypt. Players can travel across deserts, oases, villages, cities, tombs, and the Nile valley. The setting is designed as one connected world rather than a collection of separate historical cities.

Origins also reworked the series with role-playing-game systems, including levels, equipment rarity, ability trees, crafting, and quests. Its combat changed from the counter-focused style of earlier entries to a hitbox-based system with shields, weapons, and enemy levels.

The game is set before the formal Assassin Brotherhood exists. Bayek and Aya's experiences lead to the creation of the Hidden Ones, the organization that becomes the Brotherhood in later centuries. Odyssey expands the RPG format but is set in ancient Greece, not Egypt.