He is, though, the archetypal Bungie employee: simultaneously irreverent and passionately loyal; fiercely self-critical; full of excitement at the company's achievements, no matter how obscure; recruited from its devoted fanbase (in his case, the clans formed around Myth). And he has a topsy-turvy understanding of studio hierarchy, where operational chains of command are counter-balanced by meritocracy, by a ranking system based on length of tenure (from Grizzled Ancient to Newbie) and by persistent competition amongst staff to prove just how Bungie they can be.

"It's impossible to feel stable and entrenched here," Griesemer continues. "The newest designer will be sitting in a design meeting and challenge me on something that's been an established part of the Halo gameplay for years and years and years. I like having those discussions, sitting in a room and having a bunch of people just go at me. For me it's really fun if your ego can survive it, and the ideas that come out of the other side are vastly improved."

Within these walls, Griesemer can say anything, and anything can be said to him. That's one unusual thing about Bungie; one clue to the mysteries we're here, at the studio's Seattle offices, to unravel. How, exactly, do you go about making a 10/10 game? And perhaps even more crucially - how do you hold your studio together when that game balloons into a cross-media entertainment phenomenon, when you become a strategic asset in a consumer electronics war, when your self-contained world is transformed overnight into a drop in the ocean of the world's richest company? In the face of all that, how does Bungie stay Bungie?

Building your own private fortress certainly can't hurt. After completing Halo and Halo 2 on Microsoft's Millennium Campus in nearby Redmond, Bungie was the first part of Microsoft Game Studios (discounting UK-based Rare) to be allowed to break away and establish its own base of operations.

The building is a discreet, low-slung, converted warehouse store on a quiet retail park, neighboured by pancake houses and coffee shops. But step inside the huge main office space and the dark is studded with the bluish highlights of a hundred LCD panels; with two storeys of solid, free-standing closed offices at the back, it's like nothing so much as stepping right inside a Halo structure. Hardly surprising, since one of the trained architects on Bungie's art team contributed to the design.

The move wasn't just about privacy, though. "It was to get a space that was open, that felt comfortable to be in, that worked with our collaborative nature, allowing us more flexibility," says studio manager Harold Ryan, a stout, impenetrable wall of Microsoft-trained muscle who is Bungie's operational chief. "Initially I thought it was a funny joke when someone suggested we put the desks on wheels. And now, the desks are on wheels. You want to do a desk move, you just unplug from your floor box and plug back in." The desks are arranged in circles around rough disciplines, employees' physical locations shifting with their working relationships.

Art director Marcus Lehto, soft-spoken giant and veteran of the Chicago days, says free speech and inter-disciplinary freedom have always been vital to Bungie's creative health. "From the very beginning when it was just three or four of us sitting in an old Catholic Girls' School with mice coming out of the desks, to this, it's been about keeping that open communication and the structure of disciplines - we don't ever break engineering apart as a completely separate entity from art, from design." He recalls the temporary offices Bungie occupied immediately after the Microsoft acquisition: "They put us in ten-foot-high cubicles. While we were all within the same vicinity, our team started to break down within just a matter of weeks. It was amazing how much we relied on line of sight, being able to talk immediately, not having to communicate through email."

The flexible approach is about to become very important, because Bungie is looking to expand. The studio, currently standing at just over 100-strong including contractors, has just completed its biggest hiring year ever and intends to keep growing fast, partly to sate 360's tremendous hunger for assets. Partly, but not entirely. With likely less than a year of Halo 3 development left, and the end of this monumental trilogy (though not necessarily of Bungie Halo games - Ryan at one point refers to "the next Halo game" and says it will likely be a shooter) in sight, the germination of new, original projects is already underway. Bungie is about to undergo its biggest change yet, bigger even perhaps than the Microsoft 'merger' (as Greisemer insists on calling it): the move beyond being a single-project, single-IP studio.

The motivations are manifold, not least the conflict between an unwillingness to let go of Halo, and a need to escape it. Marty O'Donnell, Bungie's composer, audio director, 'ombudsman' and avuncular father figure - a former contractor in his 50s who has gradually become the social lynchpin of the organisation - puts his finger on it: "To some extent we have let Halo equal Bungie, Bungie equal Halo. Over the last four or five years I think we've got slightly complacent about our personal Bungie branding, we've become so equated with Halo, and as Microsoft rightfully decides to expand the Halo universe and have other people making it, we're like, oh... right."

"See that doesn't faze Marty or me that much," notes technical lead Chris Butcher, an energetic, sharp New Zealander and reputed 'boy genius' who joined from the fan community at about the same time as Greisemer. "But you've got to remember that 75 per cent of the people out there have only worked on Halo games. And more to the point, since they've arrived at Bungie, the only games they've worked on have been five-million-unit selling, platform-shipping blockbusters. That's a very different world to be in than working on some other game that we might do next, so there's going to be a real challenge for us to separate ourselves."

Bungie is naturally never one to shy from such a challenge. And while it's true that more projects need a bigger Bungie, it's also true, reckons Lehto, than a bigger Bungie needs more projects. "To retain that culture, it's going to be necessary for us to allow the team to break off into smaller teams where they are able to all have an impact on the project. As you grow to that 100-person-plus studio you can't have everybody having an impact on one project in some profound way."

Even if Bungie wasn't considering expanding its portfolio, though - even if it was happy to commit itself to remaining a Halo factory for the foreseeable future - the landscape would look very different now than it did five years ago. Xbox 360 will be two years old by the time Halo 3 comes out, and the tight synergy between Bungie's games and Microsoft's consoles has, to some extent, already been broken.

"The concept that Bungie wouldn't have a launch title for the Xbox 360 was almost impossible to conceive of," says O'Donnell. "That was really hard for the suits to swallow, it was like, no no no, we have to have a Bungie launch title. But I remember saying that there's nothing better than for Bungie not to be able to have a launch title, and for Bungie not to be defining the Xbox 360. I know it's scary for everybody, but it's not scary for us. We make games. We don't ship platforms. We don't push platforms. As soon as we think that that's what we're about, as soon as we think that Bungie's a platform company, we are, in my opinion, doomed." Butcher is firm in his agreement. "Even through the Microsoft acquisition, Bungie's purpose is not to make money for Microsoft and support the platform. Bungie's purpose is to make great stuff."

The surprise, perhaps, is Microsoft's willingness to see it that way, and to allow Bungie to continue to exist on its own terms. "When we first moved here from Chicago I thought it was going to be the doom of Bungie altogether," confesses Lehto, "that it was only a matter of time before either we were converted to processes that we truly didn't believe in and that would destroy our culture." He's happy to have been proved wrong. Head of production Jonty Barnes, a slender Englishman very recently arrived from new stablemates Lionhead, was stunned. "Actually, it's very much like a publisher-developer relationship. Lionhead and Bungie are equally intermixed with Microsoft, and that's quite incredible considering the geographic locations."

"Being someone who had my own business I knew that it would be a culture shock for Alex [Seropian, Bungie founder] to suddenly become a middle manager at a corporation the size of Microsoft," says O'Donnell. "I knew that Alex would probably get frustrated with it and within the next few years he did. But when we talked to Ed Fries [Microsoft's VP of games publishing at the time], that was one of the things that he absolutely assured us was not going to happen. They wanted to do everything they could to keep Bungie insulated, let it have its own culture, and not have it be too watered down."

"That was a real departure for Microsoft at the time," adds Butcher.

It still hasn't been plain sailing. "It's not necessarily a fight against forces at Microsoft that want to change things," Butcher continues, "but just the natural way things work at a large company. Microsoft has always been organised around the competition of ideas rather than the competition of groups."

"Especially it has to do with, not so much the people at the top, but some of the people out to the sides, people who think: aren't you guys just part of Microsoft?" says O'Donnell, his frustration starting to show. "'Why can't we do the same thing we do with everybody else?' It's not so much a fight, it's just that it's important for us to keep those barriers out there... I don't know, it actually is somewhat of a fight. Not everybody has the big picture, especially at a lower level." It's a fight that only "five people at the studio, tops," are ever fighting, according to Butcher. "The Bungie management team does a really good job of shielding us from these pressures," adds community and franchise lead Brian Jarrad.

The question remains: why take the fight on in the first place? Why put the 'Bungie culture' so precious to this team - "a slightly irreverent attitude, and not corporate, bureaucratic, business-focused kind of people," according to O'Donnell - in jeopardy?

The simple answer: to make Halo what it was. "If we go up there and choose to make Halo an Xbox game," says Butcher, reconstructing the argument, "we get to work with them at the cusp of something that has never been done before. We saw a chance to make the game better, not just in terms of making it a better game, but in terms of its impact on us and on the world. I think everyone would agree that Halo is a different game on the Xbox than a Halo game on PC with the same gameplay would have been at the time."

"Honestly I think Halo was so much about timing," says Greisemer. "When it came out, the platform, all the people that worked on it just happening to come together to make the perfect team to work on that game. The fact that we were in Redmond talking to the hardware guys constantly let us jump the technology forward. It was just this crucible where everything came together just in the right way." As far as the game itself goes, and the creation of the perfect alchemy of its design innovations - the two-weapon limit, the recharging shield, the checkpoints - Greisemer makes it sound easy; like riding a wave.

"We didn't have to know what we were doing, we had such powerful ideas that they just sculpted everything and we just sorta tried to stay out in front of them. Bungie's specialty is not generating ideas like that, it's recognising those ideas. It's not like we sit in a room and say, OK, let's revolutionise the health system!"

He's fairly dismissive of its much-vaunted balance, though. "Balance is not the most important part of the job. I think it's actually not super difficult to do. What's really hard is having stuff in your game that's hard-edged and different. You could make a game that's perfectly balanced where everybody just had the damage-over-time gun, right? Where everybody's health bar is decreasing at the exact same rate. What's hard is breaking out of that." He pauses and his eyes gleam mischievously. "Actually, the damage-over-time gun sounds like a genius thing."

Butcher has a much more specific, prosaic theory for what made Halo great - and, it turns out, what disappoints him so bitterly about Halo 2. "We had about four to five weeks to polish Halo at the end. No more than that. And that last five per cent is responsible for 30 per cent of the success of the game, or more. That's the period in which we really had a perfect storm. The team was all there, everything was working great, the Xbox hardware was finally there and good, and we just were able to relentlessly execute on that. The entire game came together within that four- to six-week period.

"One of the things that stuns me when I think about it, and I can't believe this is true - we had none of that for Halo 2. Take that polish period and completely get rid of it. We miscalculated, we screwed up, we came down to the wire and we just lost all of that. So Halo 2 is far less than it could and should be in many ways because of that. It kills me to think of it. Even the multiplayer experience for Halo 2 is a pale shadow of what it could and should have been if we had gotten the timing of our schedule right. It's astounding to me. I fucking cannot play Halo 2 multiplayer. I cannot do it. And that's why I know Halo 3 is going to be so much better."

There's a fair amount of criticism of Halo 2 amongst Bungie staff. Writer and community officer Frank O'Connor, an acerbic ex-pat Scot and former journalist, admits the cliffhanger ending was rather abrupt - "we drove off Thelma & Louise style". He also admits that Bungie's vocal, internal, inter-disciplinary self-analysis can be its own worst enemy sometimes: "The trick is to avoid designing or writing by committee. You have to take what's best from the input you're getting and not have it turn into that too many cooks situation."

"That's sort of what happened with Halo 2," agrees Greisemer. "Toward the end we were working on balancing the weapons and everybody was very vocal about a ton of things and I think eventually we just sort of polished away some of those hard edges."

But it shouldn't be confused with a lack of self-confidence, or bowing to public opinion. Bungie is a viciously self-critical organisation. "The pressure doesn't come from beating Halo 2 or Halo, it's all internal," says the placid, even-tempered Jarrard. "We challenge ourselves to keep pushing further and further - nothing's ever good enough for us." It's a facet of the studio's culture that everyone speaks of approvingly - proudly, even - although director of special projects Zach Russell thinks a little positive reinforcement wouldn't go amiss: "I feel like we're always talking about what could be better, I kinda wish that once in a while someone would just say: 'Hey man, just so you know, what you did there is really cool'."

Russell, whose purview extends from managing external projects like Ensemble's Halo Wars RTS to Bungie.net's stat-tracking and Bungie's own IT infrastructure, has an infectious enthusiasm for every corner of the studio's operations. "It's passion in our IT and infrastructure, and the fact that we have hundreds of servers running lightmap rendering, that we have processes for doing distributed functionality that nobody will ever see, we have a ton of tools for tracking every single crash in our game. That translates to a really high level of quality in the game because we have such passion for really low-level details that I don't know if other people get excited about."

And it's through Bungie's discovery of these tools and processes - tools and processes that are increasingly widely adopted throughout Microsoft - that what was once an unruly creative force is finding discipline under Ryan, and hoping to avoid Halo 2's crunch nightmare. "How do you go from being really really organic and essentially having no production schedule at all - which is what Bungie was really early on - into this - where there's major financial dependencies on us getting our stuff together - but still preserve that experimental thing?" asks Greisemer, framing the million-dollar question. "We now have a system for when I want to come in and do something crazy, for making it all work. In Halo 2 I would come in and say: 'Hey we're going to do this crazy thing, and it's totally going to destroy everybody's schedule and we're going to slip and there's no process for that to get worked in'."

If anything, despite the studio's increased size and the demands of the new technology, experimentation is easier now, Bungie is even lighter on its feet, and the potential for Halo 3 to spin off in radical new directions is considerable in a world where a new weapon, only recently conceived, can go from concept to prototype in a 'ridiculously short' length of time. "Now I feel like we've got this incredible framework and we can just go nuts and do anything we want to with this really solid foundation," Greisemer continues. "In fact, we've run into this problem where we started with a whole bunch of experiments and they turned out pretty well. Which one of these successful experiments are we not going to do?"

It's a good problem to have. Not an easy one, but a good one, like most of those facing Bungie: how to find more people of the calibre it already has, how to make more than one game at a time, how to work faster and better, how to stay in touch with its exponentially expanding creation, how to stay in touch with its proud self. Happily, for them and for us, Bungie seems to have a bottomless appetite for good problems.

"I had this really crazy idea for something that I'm not allowed to talk about yet," says Greisemer, "and a lot of places you'd just get shot down because it's technically very difficult or artistically hard or from a production angle it's sort of risky. But here you can get people excited about it and they're just such a bunch of geniuses that they can actually put it together and make it work."

Boxouts:

Community care
A vital tool in maintaining Bungie's identity within Microsoft, and retaining its community
of fans, has been its website bungie.net. It's also an example of the way Bungie has been changing Microsoft from within. "When I first started four years ago we were viewed as being in direct conflict with the xbox.coms of the world and the overall PR plans for Microsoft, and we had a lot of pain points." But now "Brian [Jarrad] specifically is seen as the role-model for community management within Microsoft," says O'Connor, and bungie.net is widely imitated. Bungie.net's stat-tracking Halo 2 integration was also a labour of love for the team - "one of the best experiences I ever had as an employee," says Russell - and an example of the side projects that Barnes says "would be defined at other companies as wish-list items, which are at the core of doing cool things for people who play the games".

Comic relief
The most high-profile element of Halo's expansion beyond Bungie's walls has been put on hold for now: the film adaptation, to be produced by Peter Jackson and directed by Neill Blomkamp, fell foul of budgetary disagreements with backers Universal and Fox. "Better for it to die now than be bastardised over the course of development because it all becomes about money," says Jarrard phlegmatically. "The creative spirit of the movie started to be joepardised by balance sheets and contracts." However, that leaves two more Xbox 360 projects: Halo Wars, the RTS by genre specialists and Microsoft Games Studios stablemates Ensemble, and a yet-to-be-defined project by Jackson's fledgling Wingnut Interactive. An indication of how seriously Bungie takes its custodianship of the Halo universe can be drawn from its loving incubation of the recent Halo Graphic Novel, which it edited and financed itself before turning to Marvel as a publisher. "After not ever really getting anywhere with the traditional franchise licensing model and pursuing finding a partner it just wasn't really going the way we wanted it to," says Jarrard. "One day, Lorraine [McLees], one of our art leads, just decided we should do this book ourselves." Bungie was able to approach the artists it wanted, including French legend Jean 'Moebius' Giraud and 2000AD stalwart Simon Bisley, free of the political encumbrances suffered by Marvel and DC. "It had the side effect of being a really cool morale boost for our team to see their universe, their characters, realised by people that we idolise in the comic industry."

X marks the spot
If it's possible, Bungie is being even tighter with information on Halo 3 than on its predecessor. The two brief trailers shown so far indicate that at least some of the singleplayer campaign will take place on a ravaged Earth, and that Master Chief will possess an intriguing shield device. A multiplayer playtest with US media, ahead of the game's public beta due in spring 2007, revealed a new vehicle (the ATV-like Mongoose), weapons (the high-power Spartan laser, Covenant Spiker gun and grenade, as well a reworked assault rifle) and a 'man cannon' that can fling players across maps. Reload and contextual actions have been assigned to the bumpers, leaving the X button currently, and mysteriously, unassigned.

Bungie staff won't talk specifics about the game, but it's not difficult to goad them into generalised gushing. Greisemer says "it feels more crafted" and hints at some radical new ideas, while O'Connor reckons the strength of Halo 3's singleplayer will be in its sheer scale. "Even now, you can go into the most primitive, poorly-polished encounter in any of the levels that are actually populated, and it feels better than the way you remember how awesome Halo was. On that first level there's a moment when you're in combat in an epic encounter, and also you can see over a ridge to another epic combat waiting for you to arrive at it. You can do something more amazing over there that you can see being set up for your arrival." Adds Greisemer: "In Halo, there was a lot of smoke and mirrors to make it feel better, but it was not epic combat, really. Now when you play Halo 3, it is."