Namco Bandai has filed two trademarks: All Star Battle and Project X Zone. It’s expected, then, that one of these trademarks is the name of the mystery project that’s being worked on by SEGA, Capcom, and Namco Bandai, there’s a good chance it’s the latter name. Project X Zone. Why?
You only have to look at the URL of the mystery project’s website: pxz.channel.or.jp. The “pxz” is right there as the sub-domain and acts as an acronym for Project X Zone.
Considering the similar naming structure to Street Fighter X Tekken, and the large amount of characters we can expect, it probably is a fighting game, but we’ll have to wait and see when the countdown ends.