Late last year, Microsoft opened Black Tusk Studios. The Vancouver-based outfit had big ambitions, staffing up to make a new franchise on the scale of the Halo series. As it turns out, the studio isn't satisfied with breaking ground on just one new franchise -- it's working on three more.
A LinkedIn resume (via VG247) from Black Tusk senior product manager Jonathan Browne reportedly says he's the "primary product manager on four unannounced new IP," and a "key contributor bringing these IP from the very early concept phase through green light to production." The latter part implies that each of them are in active development.
This comes amid reports that Microsoft will be debuting its console this spring, with possible plans to launch this year. It would make sense for at least some of these games to be shoring up first-party titles for the new console, and juggling four games would certainly do well for the reputation of the fledgling studio.