Liberation initially launched in 2012 as a PlayStation Vita exclusive, but saw a spruced-up re-release on Xbox 360, PS3, and PC in 2014 under the HD moniker. Fun fact: its new backward compatibility status means that all console games in the Assassin's Creed series are now available on Xbox One.
Liberation was initially marketed as an Assassin's Creed 3 spin-off (although its connecting thread is mainly just a shared time period), and follows the exploits of Aveline de Grandpré around 18th century New Orleans and the Louisiana Bayou. Eurogamer's resident Assassin's Creed expert/obsessive Tom Phillips ranked Liberation at number eight in his run-down of the series' finest entries last year, if you're curious to know how it stands among its peers.
As for Xbox One's other new backward compatible offering, Ghost Recon Advanced Warfighter is the third main entry in Ubisoft's Tom Clancy themed squad-based shooter series, and arrived on Xbox 360 back in 2006. Its then-futuristic tactical action unfolds in far-flung 2013, and was deemed worthy enough to secure a 7/10 at the time of its Eurogamer review.
"It's true that for the most part, GRAW's single-player campaign really does hit the mark, with some occasional on-rails set pieces mixing well with the tense, slow-paced precision of the strategic missions that pepper the 12-hour campaign", said former editor Kristan Reed of the game, "If it weren't for the bugs, the topsy-turvy difficulty spikes, inconsistent checkpoints, and ropey night vision we'd have no hesitation singing its praises all day long."
"The multiplayer does dig it out of a hole to a certain extent, but even then some of the design decisions are questionable and don't fully live up to the massive potential on offer [...] the truth is GRAW lets you down just when you start to believe in it, and the net result is that although it's still very good, it's simply not as polished or amazing as it should have been."
So while neither game is the very cream of the crop, each is solid enough to offer some decent entertainment to series fans. Existing Xbox 360 copies of Assassin's Creed: Liberation HD and Ghost Recon Advanced Warfighter should be usable right now on Xbox One. Alternatively, you can scout them out (here and here respectively) over on the Xbox Store.