Despite the world and his dog reporting that Bungie was hard at work on a massively multiplayer action game, it turns out the studio which created Halo wasn't being entirely serious when mentioning an MMO.
Everything was sourced from a slide during Bungie engineer David Aldridge's GDC presentation.
"An industrious journalist noticed the final slide from David's GDC deck which apparently proclaimed that we were hiring for a 'massively...multiplayer action game.' Ruh oh.
"Now, in rehearsal Aldridge was convinced that everybody got the joke. It was all in the delivery, he assured us, and he was certain it was clear that he was playfully riffing off of the recent rumours. Unfortunately, most people can't figure David out - they can't process him. And we don't expect them to. You can't process David Aldridge with a normal brain. You'd need tiger blood and Adonis DNA."
While Bungie hasn't ruled out the development of an MMO, it does seem unlikely that it would distance itself from the reports only to later reveal that the new game was an MMO all along.