The Epic Games Store has announced that Assassins Creed Syndicate is going to free this Thursday along with Faeria. These will able to be claimed on the Epic Store Store website or in the desktop app. At present, you can claim Kingdom Come Deliverance and Aztez for free.
Assassins Creed Syndicate, in my view, is the best old-style Assassins Creed game before they soft rebooted the series with Assassins Creed Origins. In Syndicate you are put in the role of the Frye twins as you travel around London. This is the pinnacle of the old Assassins Creed series and the lessons they learned into practice.