Well here's something we definitely weren't expecting to see today: Harmonix, the genius studio behind Rock Band and Guitar Hero, is apparently developing a real-time combat game for next generation consoles. A job ad on Gamasutra reveals as much, with Harmonix looking for a "Combat Designer to create real-time, single-player combat experiences for a brand new IP on next generation hardware." In other words, it would appear that Harmonix is ready to branch out from the rhythm genre.
Even more interesting is what Harmonix had to say to Kotaku when questioned about the job ad. Though Harmonix's John Drake didn't get into specifics about this new game, he did confirm that Harmonix is currently working on it, and that this is just one of "multiple new IPs" the studio is working on. Drake ended his statement to Kotaku by saying that "Harmonix is making new kickass IPs, some portion of which may have some combat."
So, Harmonix is definitely working on a new single-player IP that involves combat in some capacity, and it seems that the studio is pretty excited about it. Unfortunately, don't expect to hear much more about this new IP anytime soon; given the fact that it's intended for next generation consoles, we definitely won't be getting a reveal before the next Xbox and PlayStation have been announced. That is, of course, unless this is a Wii U exclusive, in which case a reveal may not be that far off.
Speculation about reveal dates and platforms is all well and good, but to be honest, we're just excited to see what Harmonix can do outside of the rhythm genre. The vast majority of Harmonix's games have been related to the genre in one way or another, and while most of those games have been great, the rhythm genre can be pretty restricting. It's clear the team at Harmonix is very talented, and as far as we're concerned, it's long past time that those talents be put toward something fresh and exciting.