It won't be Square Enix that acts as publisher for the upcoming Xbox exclusive Rise of the Tomb Raider, but Microsoft themselves. This was confirmed today on Twitter by Aaron Greenberg. This does, of course raises questions as to whether the game will show up on other formats or not.
It was confirmed earlier this year that the game is a timed exclusivity, but for how long hasn't been announced. The deal seems to be similar to the one Microsoft had with Dead Rising 3 and Ryse: Son of Rome. Both were released on PC almost a year after they originally arrived on Xbox One, but neither has since been released on competing platforms (most notably PS4).
In a recent statement , Square Enix said: "Yes, Microsoft will be publishing Rise of the Tomb Raider on Xbox. Microsoft has always seen huge potential in Tomb Raider and they will get behind this game with more support across development, marketing and retail than ever before, which we believe will be a step in continuing to build the Tomb Raider franchise as one of the biggest in gaming."