It's all super speculative at this point
Back in May when Microsoft first announced the Xbox One, it also promised to bring a fair number of exclusives and new IPs to the platform. While there's some stuff currently available and more in the pipeline, a title just popped up that will likely be yet another new property.
A trademark was filed by Microsoft with the USPTO in late December for the mark "Throne Together." All we know about this term thus far is that it has been classified as game software. Anything else is pure conjecture.
But, conjecture's fun, so let's speculate as to what this could be! I'm putting my money on a crossover between Game of Thrones and Drawn Together where you have to use Kinect to hit Wooldoor Sockbat with big, floppy weiners. Maybe some dragons will eventually show up, too.