Asking Bungie about the singleplayer component of Halo 2 is still useless. Journalists do their best, playing the rephrasing game until it becomes embarrassing, but no matter how they twist direct questions into innocent-sounding gambits, Bungie will not budge. "We're not here to talk about the oneplayer game" becomes the familiar refrain.

Later, we get to speak alone with Bungie's studio manager, Pete Parsons, and ask if the secrecy is an attempt to give Halo a mystique, to make a geeky sci-fi FPS interesting in the same way Fry's made Turkish Delight seem exotic. "I can't talk about the singleplayer game..." he predictably begins, but then goes on to answer the question: "It's not about teasing our fans. We want Halo 2 to be a surprise - to let gamers experience for themselves all the thrills and spills of the plot."

But keeping secrets can be hazardous. Bungie's decision to reveal absolutely nothing of Halo 2's singleplayer campaign could backfire if the game doesn't live up to everyone's expectations. And that's the problem. With nothing to go on but a short demo revealed at E3 over two years ago the world has been abuzz with expectation and wild speculation ever since.

Cheekily, Bungie has even been poking a stick into its own forum, stirring up the crackpots and obsessives with the 'OFFICIAL Halo 2 Speculation Thread': 'Earth may be a storage planet for the Flood - they are hidden under the pyramids' and 'Master Chief will hook up with one of those 'new' female marines, and will have a half normal, half enhanced kid' are two posts setting the general tone.

Parsons is unapologetic about such activity: "The Bungie.net team is a big part of the company and it's one of the things that makes us special. I think our fans realise that we're having as much fun as they are. The team has built a vibrant community ensuring that the games don't end when they get released. For Halo 2 we're going to turn it up to 11. On Live we're going to support fans with adjustable playlists and downloadable content. The singleplayer game is just the beginning."

Turning it up to 11 - is that the Edge score he's predicting? Whatever the case, this is a company supremely confident about the material it's about to release in just a few months' time. There's no sense here that Halo 2 will disappoint in any way. You can see it in the Bungie swagger, the glint in the eye of delegates wheeled out to take questions before refusing to answer them. It's as if to say, speculate away, it doesn't matter - Halo 2 will be everything you hoped for and more.

We're given a tour around Bungie's offices, which is amusing if only to watch journalists trying on full-size Master Chief costumes. That aside, it's unlike any developer we've visited. Not because it's powered by state-of-the-art technology or decorated like a plush New York apartment, but because there's no one here. Well, hardly anyone. Turns out most of the staff work the hours they want to maximise their creative energies. Clearly, one o'clock in the afternoon is a bit early for most.

"Everyone at Bungie works incredibly hard," our guide assures us. "And everyone is pretty much responsible for their own part of the game. As you can imagine, there have been a lot of late nights recently and still more to come."

At least the absence of staff members means we get longer to digest the contents of whiteboards and concept art hanging on partitions as we move around. How about this for a Halo 2 creature you've never heard of before: a Drinol Beast, a sort of hairless, grey monster with one eye - although there are other drawings of it with two eyes so you can't take for granted that it's going to make the final game. And then there's Bungie's twisted sense of humour to take into account. We wouldn't put it past the company to put a few red herrings around the place, just for a laugh. However, one whiteboard does catch our eye, chiefly because it's out of the way and unprepossessing. 'Block 4' is the title, followed by four subheadings: 'Spacestation', 'Flood Lab', 'Forerunner ship', and 'Delta Control'. Just a nugget like this is enough to whip fans into frenzies.

So far, there's little to indicate what makes Bungie special. Can it just be down to trust? The idea of responsibility is key to Parsons: "It's hard to define exactly why Bungie is special. Let's put it this way: the company only recruits the best, and there's very definitely a culture of responsibility here. It makes or breaks them. People work hard for the team but they're also working hard for themselves... they'll have a particular feature to solve or idea they want to flesh out. Also, the organic way we build the game also encourages creativity."

Parsons is an energetic evangelist for the game and seems genuinely excited about playing it himself. A large room is set aside at Bungie's HQ for an entire day of multiplayer Halo 2 gaming. Noticeably, Parsons is jumping into any vacated seat, getting stuck in and generally dragging up the averages of those away eating pizza.

We're treated to three new multiplayer levels of Halo 2, plus the Zanzibar map first showcased at this year's E3. Although there's a mood of disappointment that there's no singleplayer level on show, it's short lived. No one complains once the headsets go on and the slaying begins. (The headsets are noticeably different, with a higher build quality and adjustable parts so that they fit snugly into even the oddest-shaped ear. They will be released alongside the game.) The three new maps give a good indication of how much Bungie has improved the multiplayer component of Halo. It's familiar yet more complex and satisfying. Parsons describes it aptly: "When you pick up Halo 2 we want people to think of it as an old friend. It has all the same clothes, but a new haircut and a wad of cash in the pocket." Maybe in the UK we're not so impressed by a friend fresh out of the barbers waving a fistful of cash around, but we get the point.

Bungie does let on that the architecture contained in the maps gives a flavour of what's to appear in the game proper. Which is interesting as one arena takes place in what appears to be a large Covenant craft. It's broadly cylindrical, with purple and pink paths twisting around the outer rim and up to an overhead footbridge. It's the smallest of the maps we play and even with just a handful of players it's difficult to move a few paces without meeting a foe face to face.

The second consists of a series of ramps zigzagging their way up to a large square platform; there's also a jump pad that can take you from the lowest level up to the top in an instant. It's a more precarious environment and a couple of Covenant swords ensure that close melee combat is a significant factor. The final map is the largest, boasting a central atrium complete with huge pool and coconut palms. Several passages, rooms, high balconies and alcoves surround this area. The rocket launcher is the most devastating weapon here, and explosive canisters littered around the labyrinthine corridors ensure that one stray bullet or grenade can get you a kill, or killed.