On April 14th, the Xbox Live service for the original Xbox shuts down for the final time. It takes with it the multiplayer support for Halo 2 - the game which showed the world how console multiplayer should be done, and proceeded to dominate the Xbox Live stats for years. Eurogamer took the opportunity to speak to the team behind the game, and discover the tortured development process behind a modern classic.

It's hard to remember that there was a time when Halo wasn't a colossus of the games industry. These days, updates to Bungie's epic science fiction franchise punctuate the release schedule for the Xbox 360 like exclamation points - it's a pillar of the platform, the game series that brought credibility to both the Xbox itself and to the Xbox Live service. Its hero, the Master Chief, is an iconic figure in pop culture, and the series is one of the most popular online games in history - with Halo 3 still being played by huge numbers of people every night, despite the meteoric success of games like Modern Warfare.

It was not always thus. Today, Halo: Combat Evolved is remembered as being the tentpole that supported the whole Xbox launch, the cornerstone around which Microsoft built its entire console business - but Jaime Griesemer, who was a design lead on Halo 2, says that at the time, things weren't so certain.

"We were under pressure to prove ourselves and the game," he recalls. "We had some early previews with really bad framerate, a lot of disappointment that we had changed platforms, and an enormous amount of scepticism that you could make a good FPS on a console. Expectations were so low that the Microsoft marketing people were talking about putting their money behind other launch titles."

They didn't, of course, and the rest is history. Halo launched in November 2001, and was a critical and commercial success of almost unprecedented scale - achieving one of the highest Metacritic scores in history, with almost universal acclaim from reviewers (Eurogamer is mocked to this day for awarding it 8/10, the "low" score probably reflecting the site's roots in PC FPS gaming more than anything else). Half of all Xbox consoles sold for months after launch were sold alongside a copy of Halo. By April 2002, a million copies had been sold.

As the sales figures mounted, Bungie knew that Halo wasn't just a game any more. They had a franchise on their hands.

"We didn't plan Halo as a trilogy," explains Joseph Staten, who was writer and cinematic director of Halo 2. "But during Halo 1 development, we certainly had strong ideas for extending the story and gameplay experience that we knew we couldn't fit into one game. Success brings creative freedom but also heavy expectations; when we started brainstorming for Halo 2, we knew we had publisher support to execute on these deferred, more ambitious ideas."

As work on a sequel began, the team started thinking about where it wanted to go next with its newly created franchise - and, perhaps more importantly, where it hadn't been able to go with Halo: Combat Evolved. "Your initial goals with a sequel are always the same," says Griesemer, "to finish all the stuff you had to cut from the first game. And we had to cut a lot from Halo 1, so we had a lot of ideas we were ready to move on."

"It's very difficult to describe the feeling of shipping a game," says Chris Butcher, engineering lead on Halo 2. "There's tremendous pride at first, but that quickly wears off and all you see are the flaws. Then you're motivated to do better next time - that drive to improve ourselves is a core part of the Bungie culture, it's something I love about working here."

With that internal drive (Bungie's developers are "always, always our own most severe critics", Griesemer says) combined with the external pressure from Halo's newfound fanbase, each part of the team set to work on ambitious plans to improve its own aspect of the game. Enormous lists of features were drawn up. Much of Halo's engine had been hacked together in a massively rushed development period - "we were taking advantage of the fact that the Xbox hardware was more powerful than the baseline PC at that moment, so we could do things in a short-cut, hacky way and just get it working," explains Griesemer. That work would all be thrown out, and a fresh start made on a new, top-of-the-line game engine.

"We had learned so much about the console and how we could take advantage of it," says Butcher. "We had so many new directions we knew we could go in. We tried to take it all on simultaneously, and we delivered an almost complete rewrite of the engine."

Not only was the engine rewritten - it was now going to do things that Combat Evolved hadn't dreamed of. One of those, and perhaps the single most important reason for Halo 2's enduring fame, was online multiplayer.

"The one area in which the success of Halo 1 was totally surprising to us, and completely changed how we thought about Halo 2, was LAN parties," says Butcher. "We never really thought that people would do a lot of playing Xbox multiplayer on LAN, even though people in our office played it all the time... Well, it only worked five weeks before we shipped the game, but in those five weeks we played a lot of Halo multiplayer!"

"We had a lab full of Xboxes on a LAN, so we played 16-player CTF every single afternoon," Griesemer remembers. "It was fun, so this was what we designed for - but when we shipped, the vast majority of our fans never got to experience that. They were playing four-player split-screen on the smallest maps. There was a total disconnect."

"We looked at the small set of fans who were able to do this," continues Butcher, "and just how much they were enjoying themselves, and asked ourselves if we could bring that to everybody. That would be something really special, really unique."

Halo 2 online multiplayer was born in that moment, and with it, arguably, the entire success of the Xbox Live service. It feels, to an outside observer, like a momentous moment. To Bungie, however, it just felt like a logical progression.

"Bungie has always been about multiplayer," says Griesemer. "If you look back, Myth was about multiplayer, Marathon was about multiplayer... The first real Bungie game was Minotaur, and that was multiplayer-only, which was crazy at the time!"

"We're competitive people," interjects Chris Carney, multiplayer designer on Halo 2. "It always feels like a logical extension to say, hey, that's pretty cool, but what if we did that head to head?"

Butcher agrees. "It's just a good way of testing out your design ideas, right? You might think that some system is good, but until you try to use that system to kill your co-workers, you're not really going to be pushing its limits."

"We try to start with multiplayer for everything," Butcher continues - an uncanny echo of the design philosophy espoused by Blizzard's design boss, Rob Pardo, in an interview with Eurogamer last year. "Even on Oni, although we didn't end up shipping with multiplayer, we did build a multiplayer mode and beat each other up in the office, which helped to tune the combat."

While plans were hatched for ground-breaking multiplayer, every other part of the company was creating equally ambitious plans. An epic narrative arc was emerging, with a huge set of missions and environments to support it. New gameplay features were being created, some in response to perceived weaknesses in Combat Evolved, others entirely new - and of course, this new engine, designed to push the Xbox to its limits, was being built from scratch in the background.

With the gaming world watching, it was time for Halo 2 to make its grand entrance. A cinematic trailer had given gamers a glimpse of the sequel in September 2002 - but it was at E3 2003 that we would get our first proper glimpse of what was next for the Master Chief.

There are a handful of E3 demos which live on in the memories of gamers and journalists - videos or demos so thrilling that they fuelled excitement for their games, and even for console platforms, for years afterwards. Metal Gear Solid 2, shown off at E3 ahead of the launch of the PS2, is a good example. Halo 2 at E3 2003 was of the same ilk.

A short demo, played on stage, showed the Master Chief back on Earth, flying into the Covenant-occupied, futuristic city of New Mombasa. Amidst the skyscraper peaks of the city, warfare on a scale only dreamt of in the original Halo raged across the streets. The Chief had learned new tricks - he could dual-wield weapons, and board enemy vehicles by kicking their drivers out of their seats. The action was fast, cinematic and exciting. Everyone who saw the trailer walked out with their blood pounding faster, and with Halo 2's release date seeming an impossibly long way away.

Everyone, perhaps, except the Bungie team themselves - who probably walked out of the demo theatre with more mixed feelings.

The public loved the new ideas like dual-wielding and vehicle hijacking, both of which had been key objectives in the new design. The demo itself looked polished and accomplished - more like a game in the final stages of development than one 18 months from launch. However, the demo, unfortunately, was smoke and mirrors. Behind the scenes, Halo 2's development process was rapidly becoming a waking nightmare.

"The graphics engine that we showed at E3 2003, driving around the Earth city... That entire graphics engine had to be thrown away, because you could never ship a game on the Xbox with it," Butcher sighs. "Through putting ourselves through hell, we were able to do a five-minute demo of it, but after we came back from E3 we had to admit that this graphics engine was never going to work - it was never going to support the kind of environments that are really important for a Halo game. So we literally scrapped the entire graphics engine and started from scratch."

"Even that whole environment, the Earth city, was way too big for the engine at the time," adds Carney. "We ended up cutting out huge parts of geometry from that level, so you never actually saw that."

This was just the most prominent symptom of a wider problem. Bungie's ambition was catching up with it. New Mombasa wasn't the only level that had to be unceremoniously trimmed in this way. The decision to entirely rewrite the tech behind the game had meant that for over a year, there was no working version of Halo - leaving the design and art teams working on assets without being able to test them.

"We were building stuff that just couldn't be played, in any engine," says Butcher. "We built, and detailed, and went a huge way down the path with a whole bunch of environments and levels for the game that just totally didn't make it. If you look at the level with the Flood, inside the quarantine area - that is the remaining 20 per cent of a gargantuan, sprawling level that was meticulously built and hand-constructed, but that could never, ever have shipped in any engine."

"We made a scope mistake on the single-player side, too," says Griesemer. "If you look at our original plan for Halo 2's single-player campaign and the story we were going to tell, this basically adds up to Halo 2 and Halo 3 combined. We didn't trim that back nearly enough and ended up having to force it, and that's why you got the ending you did."

"The cliffhanger wasn't part of the plan," confirms Staten. "And yes, over-ambition was absolutely the cause."

Multiplayer, too, had gone awry. "We took some steps towards a bigger style of objective game," recalls Carney. "We tried that for a while - a month or two, maybe... Actually, it was a lot longer than that. We even built environments to support that, and then realised that it just wasn't the correct road to go down at that time.

"It was too ambitious. We had a lot of ideas about other games we'd played, and things that we really wanted to try - but when we got in there, we realised that it was going to require a lot more effort to make it as good as our single-player and our standard Slayer and CTF experiences. We had to cut our losses and just ship with what we were all happy with."

So, the painful process of scaling back Bungie's soaring ambitions began - and painful is certainly the word. Rapidly approaching a year before launch, the team had no engine, environments that couldn't possibly work in any engine, features that were only half-implemented, a sprawling story that would eventually require two full-sized games to tell and a complex multiplayer mode that would simply have to be scrapped.

The following year would be the toughest time many of the Bungie staff had experienced in their careers. "I had a log that I kept," says Butcher, "of the times I went into work and the times I left work. Day after day after day, seven days a week, getting in reasonably early and then not leaving before 11 at night. Seven days a week, for months and months..."

"It was the most brutal development effort we've gone through," says Carney. "We're so much more organised and focused now - mainly because some of us think back to that experience, the lack of daylight, the poor hygiene... These are things we just don't want to happen again!"

"One of the things I always say when people talk about crunch now, is that the crunch we do now is the good kind of crunch," adds Butcher. "It's the crunch where you're putting in the hours because you really want to, because you know it's going to make the game better. The crunch on Halo 2 was, 'Oh my god, we're f***ed. We're all going to die.' Months and months of that emotional, negative tone was really hard to deal with - but at the same time, we did a lot of awesome work."

Again, to an outside observer, this seems incredible. How could a long-established studio, with the backing of the world's biggest software company, making a sequel to one of the most critically acclaimed games in history, have presided over such a disaster?

"It happened on Halo 1 as well," admits Butcher. "Of the 25 planned missions for Halo, we shipped 10. Part of the problem is that as team size grows, all the really informal, seat-of-your-pants stuff you've been doing just doesn't work. On Halo 2, we had not levelled up as an organisation enough to be able to even comprehend that that could be a problem, let alone try and solve the problem. We were like kids going through a messy adolescence, but with tens of millions of dollars' worth of budget and the whole world looking at us."

Butcher maintains, however, that the over-reach which turned Halo 2's development into a nightmare was the product of Bungie's own optimism and ambition, not of hubris brought on by the success of Halo.

"I don't think people were sitting around with money-hats on going, 'whee, we can do anything we want!' - it was really just a case of saying, OK, we've done Halo, now I think we should make another of these games because there are a lot of awesome places we still want to go with this universe," he says. "So, how much awesome can we pack into this game? We thought the answer was a lot of awesome, and it turned out to be roughly a quarter the amount of awesome we'd thought..."

Even as the team fought to bring the project under control, though, there were still shining moments that stood out for them - and hinted at the success that Halo 2 would eventually become. Butcher recalls finally getting the network code up and running for an internal Alpha test of the multiplayer in January 2004: "At that point, I knew that we were going to make it, and that it was going to be an awesome multiplayer experience."

For Griesemer, the Eureka moment was getting the vehicle boarding mechanic working. "The first time that we got that working, it was clear that vehicle combat had gotten a whole lot more interesting. We had it mocked up for the E3 demo... It felt so good. I was one of the guys giving the demo, and there were several moments where you could hear the whole audience gasp or cheer. You could tell that certain mechanics were going to go over really well... Boarding, dual-wielding, the boost on the Ghost, the way the Brute roared and charged at you..."

As the end of 2004 approached, Bungie's frantic work pace increased. They knew that this would be the last big Christmas for the Xbox, with the 360 due to launch before the end of 2005. Halo 2 had to hit its date. The pressure was intense.

"We absolutely could have used another couple of months to polish, but then we would have missed the last Christmas... It really wasn't an option," says Griesemer. Surprisingly, though, the team doesn't envy the ability of developers like Valve to state "when it's done" as their release date. "The problem with 'when it's done' is that it would never have been done," admits Griesemer cheerfully. "We could create and scrap 20 versions of the game and never ship any of them."

"Moving to that kind of schedule would only have caused us to lose our focus on getting the game completed," concurs Butcher.

The need to cut features and content didn't go away as the game's final year in development progressed. "Reconciling [our ambition] with reality was a brutal process," says Butcher, "because it happened so late. We were still cutting features only four to five months before the game went gold.

"There's a famous drawing that someone did on a whiteboard in the team's space that shows a plane on fire trying to land on a runway, and people are jettisoning cargo crates out the back of the plane in order to try and get it on the runway. Every crate has the name of a feature we had to cut... In the end, we ran out of room on the whiteboard for all the crates."

Finally, however, Bungie managed to get its plane onto the runway. Halo 2 shipped on November 9th, 2004. Anticipation was at fever pitch; 1.5 million copies had been pre-ordered, an industry record, and 2.4 million were bought in the first 24 hours on sale, giving Halo 2 the highest grossing opening weekend for any entertainment product, ever.

Griesemer, who had been involved in the focus testing for the game, knew that Bungie had a hit on its hands. The team's obsessive approach to intensively testing its gameplay was really born on Halo 2, which gave Griesemer a unique insight - he had stats, on paper, which said that people loved the game.

Not everyone in the company was convinced. "I remember having a lot of conversations with people who thought we'd screwed up, that we'd destroyed the franchise, driven it over a cliff," he recalls with a laugh.

Halo 2 scored almost as highly as its predecessor with reviewers - no mean feat for a sequel to a ground-breaking game. Some gamers, however, were less convinced, for two key reasons.

One was the cliffhanger ending, a symptom of Bungie's desperate need to cut features and levels from the game in order to hit its ship date. The other was a secret which Bungie had jealously guarded since the outset - a second playable character, the Arbiter, a Covenant Elite who allowed you to see the war from the side of the Master Chief's implacable foes. A noble warrior betrayed by his own leaders, the Arbiter lends surprising depth to Halo 2's otherwise gung-ho narrative. Some fans, however, hated him.

"Some of that backlash was on account of the heavy-handed marketing that set expectations for defending Earth against the Covenant," says Brian Jarrard, Bungie's community lead. "I think, even more so than playing as the Arbiter, the thing that people were disappointed with and angry about is that they were promised this experience, through the marketing, of being really backs against the wall, Earth's under siege, we're going to do all we can to save our home planet... In reality, the game only had two missions that actually did that."

"The original plan had you returning to Earth at the end - which you did, at the end of Halo 2, for about three seconds before it abruptly ended," says Griesemer. "I think if we'd been able to finish that last couple of missions and get you properly back on Earth, a lot of the reaction would have been placated."

Butcher disagrees. "I don't think so. I think it really was that a bunch of people thought they were going to play a war movie - they were going to play Medal of Honor, with aliens, and that was not the game we were building."

For his own part, Butcher really liked the Arbiter levels. "I'm a player who cares a lot about the story and what's going on, and why the world is the way that it is," he explains. "Players that don't, that are really just there to experience the action, some of them skipped the cut-scenes that took you from the Master Chief leaving Earth. If you skip that, the last thing you see is that you're in a Pelican leaving Earth, and then you're some dude carrying an energy sword with Grunts around you trying to kill you."

"I think the Arbiter is a much more interesting character," adds Griesemer. "He's got a detailed arc - he really changes over the course of the games - whereas the Chief is literally the exact same guy at the beginning and the end. He's in cryosleep, ready to get thawed out and kick some more ass later."

"Halo is a war story, and we felt strongly that telling one side of the conflict was only half of the story," explains Staten. "That was the reason for the Arbiter - to offer another, compelling point of view on a war where telling friend from foe wasn't always clear-cut. We knew we had a trilogy on our hands, so we were looking past the shock of playing as the enemy to the eventual, allied push against the Flood led by the Chief and the Arbiter in Halo 3."

In the final analysis, Griesemer is happy that the team decided to introduce the Arbiter, despite the backlash. "I'd much rather experiment and do something surprising, and not have everybody appreciate it, than just turn the crank and do another alien war movie with a space marine..."

The single-player lives on in players' memories, of course - but in the years since 2004 it's the multiplayer which has kept Halo 2 alive. Even in the face of the Xbox becoming obsolete and countless other online games being launched, Halo 2 has retained a core band of fans who remain devoted to the game. Perhaps even more so than the sales figures or the critical acclaim, it's this which best illustrates Halo 2's success.

Yet if this is a story about a game whose tortured development ended up creating a brilliant, if flawed, modern classic, then there's a key question that remains unanswered. This industry is no stranger to nightmarish development processes, but it's far more common for the games they produce to be Daikatana than it is for them to be Halo 2. So what is it that made Bungie's messy, frantic development process turn out a gem, while others struggle to produce clods of dirt?

"I think it's because the places where Halo 2 did succeed, like Live, like the single-player combat, are such bright spots," says Griesemer. "Looking back on it as a player, that's all you see. For us looking back, all we really see is..."

He pauses, and Carney finishes his sentence for him in a grim tone. "The wreckage," he says.

"Yeah," says Griesemer. "The places where it didn't succeed."

There's a momentary silence. "Oh, I don't know," says Butcher, eventually. "I went back and played a bit of Halo 2 about six months ago, and the part where you're playing as the Arbiter, and you come out and see the quarantine zone, with the Corrupted Library... Just coming out and looking at that sky! There are moments in Halo 2 that really give me chills. The low points are much lower than we would have liked, but the single-player had some amazing moments."

"If the creative process is easy," concludes Griesemer, "it probably means you're not doing anything interesting. Any really cutting-edge, triple-A, forefront-of-the-industry type creative process is going to be a little bit painful. It's just whether you're really working on something great, or whether it doesn't come out that well... You never really know until the end."

Five years down the line, as Halo 2 takes its final bow with the closure of Xbox Live services - "a really poignant moment for me, actually", admits Butcher - the Bungie team knows the verdict. Halo 2 was their difficult second album; the victim of over-ambition, the product of a tortured gestation period, flawed and incomplete. If there were ever a testament to Bungie's talents, it's that for all that, it remains a masterpiece.