With a spin-off RTS game, multiple novels and an expanding range of figurines all on show this week at Comic Con 2008, Microsoft has insisted that its strategy is to "explore not exploit" the Halo universe.
Frank O'Connor, who oversees the franchise at Microsoft Games Studios, headed up the Halo Universe panel at the San Diego event, in which representatives of Halo Wars developer Ensemble, Bungie and toy manufacturer McFarlane joined Halo novelists to discuss the future of the franchise in front of a packed audience of fans.
Speaking to our sister site Eurogamer.net immediately after the session, O'Connor, former Bungie community manager, said that content so far had only scratched the surface of what is possible.
"The Halo universe is really, really big now," he said. "Literally the Halo games have only covered one year; a couple of months within a year in fact.
"We have a really detailed story bible, we do really have it all planned out. There are so many areas of the universe to explore, the real challenge is picking which is the most exciting area for people. Is it UNSC Marines fighting alongside Spartans against the Covenant? Or is it what happens next after Master Chief's appearance in Halo 3?"
O'Connor and the other panellists, including Tobias Bucknell, author of upcoming novel Halo: The Cole Protocol, spent most of the hour-long session fielding questions from fans, many of whom had squeezed into their favourite Master Chief costume for the day.
"We have a well defined, carefully orchestrated, properly planned universe to explore not exploit," O'Connor added. "And that's the tricky part: what are the things people want to do? We have to pick things that people want. That's what you see with the range of McFarlane toys - people want their armour permutation.
"Give them things they really want and make sure they're high quality is the formula."