From February 21-28, you’ll be able to get Assassin’s Creed Syndicate for free as well as Faeria, replacing the current free offerings: Kingdom Come: Deliverance and Aztez.
I know that some Assassin’s Creed games leave a nasty taste in your mouth, but Syndicate actually ranks up there with the better of them and was a huge improvement over its predecessor, Assassin’s Creed Unity. In Syndicate, you’ll find yourself thrust into London, and there are two different protagonists. It also stands out as it’s the last of the AC series that wasn’t a RPG.
As for Faeria, it’s available for free during the same time period, but it’s nothing more than a card game with a “unique living board.” Apparently, it’s the only card game of its kind, something attributed to it being possible to gain all 300 cars in less than 50 hours. Either way, be sure to at least snatch up AC Syndicate. Once you’ve claimed it and downloaded it, it’s yours to keep.