What was the first title in the Assassin's Creed series to use the RPG-style level system?

Assassin's Creed Origins was the first Assassin's Creed title to use the series' RPG-style level system.

Released in 2017, Origins introduced character levels, experience points, gear rarity, loot, skill trees, and enemy levels that affect combat difficulty. These systems changed how players approached missions, exploration, equipment upgrades, and battles compared with the more linear progression of earlier mainline games.

The RPG structure supported Origins' large-scale recreation of Ptolemaic Egypt. Bayek could gain experience from quests and activities, collect weapons with different attributes, and improve abilities in hunter, warrior, and seer categories. The approach continued and expanded in Odyssey and Valhalla.

Earlier games had upgrades, money, and equipment progression, but they did not use the same broad level-based RPG framework. That distinction is why Origins, rather than Syndicate or Unity, is generally identified as the transition point.