XLGames' partnership with Take-Two Interactive, as well as the fact that XL would be making an existing Take-Two property into an MMORPG.
This morning, various Asian gaming websites confirmed that said property is the venerable Civilization series that began way back in 1991. Details on the new game are sparse, but Google Translate versions of the news articles indicate that XL has begun "large-scale recruitment of MMORPG developers [...] including server [programmers], client programmers, artists, planners, project managers, story designers, [and] mission designers."
Prior to its involvement with the Civilization franchise, XLGames was known exclusively for ArcheAge, a fantasy sandbox MMO that is currently undergoing closed beta testing in Korea.
[Thanks to Mark for the tip!]