Game of Thrones: Ascent. In a lengthy and detailed developer blog, studio Disruptor Beam outlined the challenges it sees with keeping players engaged in GoTA at the endgame point and how it plans to address those challenges.
The main problem, it appears, is that there currently isn't enough to do after finishing volumes one and two of the story. Disruptor Beam determined that the lack of options upon the completion of the story leaves players with no reason to play, noting, "There needs to be something more to our endgame."
The studio has a two-part plan to keep players engaged. The first is item enhancement, which allows players to modify items to adjust their attributes and unlock new abilities. Improved items can be made permanent so they persist through reincarnation. The second part is alliance vs. alliance combat and diplomacy, which enables players to create alliances of up to 500 members and declare war (or form peaceful bonds). Alliances will be able to own camps and use those camps as launch points for attacks against other alliances.
According to Disruptor Beam, both of these features are still in the deep testing phase. The studio hopes to have them rolled out in the next few months. In the meantime, it appears as though Game of Thrones: Ascent is growing more and more into a fully featured MMO every day.
[Thanks to Dengar for the tip]