Spencer was coy about the announcement, however, stating in an interview, “Fans of Rare and Rare IP I think will be pleased with what we’re going to show at E3. We had a limited amount of time today and a lot of story to tell. But Rare remains an incredibly important part of our development capability. That historic IP that they’ve built I think can play a real important role on Xbox One.”
The IP is likely Rare's fighting game Killer Instinct, since Microsoft and FOX had an to allow the former to use the name for videogames.