https://www.gamespot.com/articles/free-xbox-one-games-with-gold-for-june-confirmed/1100-6459243/

It looks like June 2018's free Games With Gold lineup has been revealed, at least for one part of the world. A post on the German version of the Xbox Wire reveals that Assassin's Creed Chronicles: Russia, Smite Gold Bundle, Sonic & All-Stars Racing Transformed, and Lego Indiana Jones 2: The New Adventures will be free at different points in the month. [Update: Microsoft has confirmed June's Games With Gold lineup consists of the aforementioned games.]

Assassin's Creed Chronicles: Russia is part of the Chronicles trilogy of 2.5D side-scrolling platformers; it is free on Xbox One June 1-30. The other free Xbox One game is the Smite Gold Bundle, which packs in extra content for the free game such as 20 more gods and other items such as skins; it will be free on Xbox One June 16-July 15.