Bigger-than-life Xbox hero the Master Chief returns in the new game Halo 4,out Tuesday, with a sparkling high-def sheen and a willingness to letplayers know what's going on behind his once-impenetrable mask.

In the years since Halo: Combat Evolvedserved as the Master Chief's debut - and helped launch the originalXbox system in 2001 - the cybernetically enhanced and armored spacemarine has been a man of few words. However, his preference for ploddingforward and mowing down enemies has not hindered the series, which hassold more than 46 million copies and grossed $3 billion worldwide.

In crafting Halo'scomeback, the new Microsoft-created studio 343 Industries decided thatplayers would like to learn a bit more about what makes the Master Chieftick. At Halo 4's outset, he awakes from cryogenic sleep nearly five years after the events in 2007's Halo 3.An imminent interstellar threat has emerged, as has the potentialdemise of his longtime artificial intelligence guide, Cortana. You hear his voice more often and understand his link to Cortana in a more meaningful way," says Geoff Keighley, host of GameTrailers TV on Spike. "While you never see his face, I wonder if sometime we will finally get to see him take off the mask."

Thatdoesn't happen in this game ($60, rated M for ages 17-up), but thosewho play in its most difficult setting ("Legendary") will be rewardedwith a look at his eyes without his helmet on. As the first Halo release since the franchise-founding studio Bungie handed the creative baton to 343, Halo 4has plenty of drama as well as action. "One of 343's goals was to tellmore of Master Chief's story and make him into a person, not just a suitof armor," Keighley says.

Quickly after the Master Chief isawakened, he and Cortana find themselves marooned on the planet Requiem.The approaching seven-year limit to Cortana's life adds urgency to hissearch for an escape plan; in the Halo world, AI programs lastonly that long. "We wanted to place the Master Chief in circumstancesthat would force him to take stock of his own humanity and force him tochange," says the franchise's creative director, Josh Holmes.

Complicatingthe situation: There are others on the mysterious planet, includingforces of the Covenant, the aliens with whom humanity and the UnitedNations Space Command had apparently reached a truce at the end of Halo 3.The Covenant has discovered what appears to be an installation createdby the Forerunners, an ancient, technologically advanced race creditedwith building the halo structures in the earlier games.

Despite these thematic threads from earlier Halo titles, 4 feels new, says Francesca Reyes, editor in chief of the Official Xbox Magazine."The music feels like it's tailored to very specific moments, to drawout a response from gamers, and there's a retooling of how the weaponshandle and sound," she says. "It's a very polished product, but that initself isn't the game's biggest feat. It's more that they've used thosetechnical accomplishments to support character, storytelling and keepingyou immersed in the moment."

Beyond the game's story mode are newweekly Spartan Ops missions playable by one to four players and a newonline multiplayer War Games mode that can handle up to 16 players.

Microsoftand 343 hope to captivate fans for a long time. "It's our job to ensurethat we have a universe you can tell stories in over the next 10 to 20years," says 343 studio head Bonnie Ross.

While some reports have Halo 4as the first in a trilogy, that's not necessarily so. "I like to callit a saga," Ross says. "It isn't a set number of stories. There is astory arc that we are very interested in telling across multiplemediums."

Among the other Halo story devices:

-- A theatrical-quality trailer produced by David Fincher (The Girl With the Dragon Tattoo) shows the Master Chief as a youth, being indoctrinated into the Spartan program.

-- The five-part live-action video series Forward Unto Dawn(Episode 5 landed Friday on unfolds an early episode inthe Master Chief's career. He rescues several students whose academy isunder attack; some will become well-known characters in the game goingforward.

-- Weekly Spartan Ops episodes begin with the arrival of Halo 4 (free for Xbox Live Gold subscribers). Each CGI-animated story segment - the events take place after Halo 4 - segues into a new playable mission.

-- Novels, such as The Thursday War by Karen Traviss, released last month, explore the post-Halo 3 universe, while another series by Greg Bear looks at the Forerunners. His third book, Halo: Silentium, is due Jan. 8.

"We've been seeding those novels with information that ties into and sets up a lot of the story points in

Halo 4

," Holmes says. "This grand story design connects all these dots throughout the universe."