A resume belonging to a lead programmer at Ruffian Games suggests the studio has been contracted out for work on "a multiplayer map for a first person, melee combat game based on the CryEngine" for Xbox 360.
According to Superannuation, who found the CV online, the game is described as "a first party CryTek project which [Ruffian] were contracted onto," and the team's task was to work on "melee combat [with] AI capable of evaluating dynamic combat situations and working as part of a team."
The resume also mentions an "unannounced third party project using CryEngine 3" which "makes extensive use of the Xbox Live server platform and Kinect."
Super believes these two descriptions point to a future announcement of multiplayer for Crytek's Kinect-based title Ryse, despite the linear single-player nature of what has been shown so far.
Neither Microsoft nor Crytek have said the game will be exclusively single-player, so it's quite possible a multiplayer announcement is coming in the not so distant future.
Still, take this as a rumor until more is revealed by the developer and publisher.