Peeking Into Blizzard’s Development Process

Initial concept plan for Lake Wintergrasp. Basic... Blizzard Entertainment have a reputation for being “tight lipped”, and not announcing details about the games they develop. And since Blizzard have a lot more freedom than the developers that are closely regulated by their publishers, they should be able to talk openly.

But having listened to many of their senior developers talk during the recent Paris “WorldWide Invitational“, I suspect actually, they just don’t know yet.

Increasingly publisher-driven games tend to be heavily pre-produced, then implemented by programmers who work for hire: The details are known a long time before release, and the only reason not to talk about them is competitive. But if you don’t have such a precise battle-plan, you can’t release information with any real certainty. So you either get a reputation for saying little, or get a reputation for producing games that ultimately exclude many “expected” features.

Blizzard are one of the most successful game developers, so they must be doing something right. It is interesting to try and understand how they develop games. On this page:

Box: Art Basics in Starcraft 2
A prelude – some key themes behind in-game artwork:

  • Strong silhouettes, with dynamic “bad arse” pose. This makes it easier to identify items and (military) units.
  • Exaggerated proportions. For example, the Starcraft 2 Terran Marine, has a tiny head with super-hero proportions.
  • Bold colours (“red rules”), to allow the player to determine their units from the enemy.
  • Oh, and lots of explosions, carnage, and big guns. Did I mention big guns?

Redoing Half of It

Start with Samwise Didier’s (art director) comments:

“Art isn’t finished until the game ships. […] Every time we have a finished race, we end up redoing half of it […] and even then we’ll patch it for 10 years.”

Why redo “half” of all your game assets, when you could save time and money by getting them right first time?

Art is first completed to match the original design intention, but then the purpose of the thing may be changed radically by the design team. That requires new art or animations. Redesign of art or animations typically occurs when the design team are “80-90% sure” they have the design right. For example, Starcraft 2’s “Thor” unit has evolved radically over the game’s development, such that many of the original animations are now used for the “wrong thing”. Once the design purpose of the unit settles down, those animations will be redone.

Design generally leads art. This creates “a better game” (Samwise again). But sometimes artists can create “something cool”, which designers then make work.

The design teams are continually evolving content. In this Gamasutra interview (which is an excellent companion read to this article), Rob Pardo denies Blizzard use an entirely iterative approach:

“You can’t really iterate until you have some stuff built. Unless you have enough art and gameplay infrastructure in the game, you can’t tell if you’re going in the right direction.”

Evolving Design

While there is some evidence of quite detailed initial prototyping (from the first demonstration of Diablo 3), there is considerable scope for change as a new part of a game world is developed. The box below provides some examples.

Box: Designing a New World of Warcraft Zone
Examples were given of how World of Warcraft’s (WoW) Northrend dungeons (for example, The Oculus), “outdoor” PvP areas (Lake Wintergrasp), and PvP arenas (for example, Dalaran Arena) were designed. They all follow a similar approach:

  1. Concept art: What’s the generally look and feel. (In one case this was cited as coming after the next stage, so the first 2 stages may inter-play.)
  2. Design layout: A simple 2D plan with dimensions. Is there enough space to hold all the enemy creatures? How much travel is required between encounters?
  3. Block-out: A simple 3D model, with no artwork. This allows people to actually play the game within the new environment, using a game client and normal game abilities. They get a feel for what works, and what does not. Can all tactics be used? Does the camera (player’s viewpoint) allow a clear view of the action?
  4. Full artwork: More detailed models and textures. Even at this stage, balancing changes can still be accommodated. For example, Lake Wintergrasp is built on an ice-covered lake. Siege vehicles have to use bridges to cross water, but those on foot can swim. The balance of play between those 2 groups can be altered simply by changing the amount of ice-covered water. That does not require dramatic changes to the artwork or environment design.

The third stage is critical, because it allows the playability of the zone to be tested, without (potentially) wasting time perfecting the zone visually. The very rough nature of the 3D model allows quick changes to be made, tested, changed again, and so on, until the result feels right. There’s a very strong parallel to David Law’s paper mock-ups – the most basic level of prototype that allows designers and potential users to get a feel for whether the design is right.

What the box above does not state is the time-line: Lake Wintergrasp, for example, was announced last year. But it is not yet close to finished: The art and environment is partial, with certain mechanics and balancing within the zone still unknown. Yet this is content that we can expect to see by the end of 2008. If the entire game were built like this, almost nothing would be known for sure until quite close to the game’s release.

In practice, some phasing of development is evident. In the first 2 WoW expansions the early (lower-level) content tended to be completed before the later content. So in Wrath of the Lich King, the Howling Fjord was somewhat playable by Summer 2007, when it was first previewed, while areas like Lake Wintergrasp were still a hole in the map. By Summer 2008, the Howling Fjord was almost complete, and Lake Wintergrasp had developed into a semi-textured zone, with the design summarised, but not detailed.

Even Death Knights Evolve

The box below describes the design process behind the new class in WoW’s Wrath of the Lich King expansion, the Death Knight.

Box: Designing a Class – The Death Knight
Key steps, in order:

  1. Inspiration: Inspiration for the class comes from concepts and lore (story) in all the Warcraft games. For example, the Arthas Storyline in Warcraft 3, with natural links to Northrend (the continent added with the same expansion that introduces the class).
  2. Philosophy: What does the class do? The Death Knight has both “tanking” (acting as a focus for an enemy’s attacks, while other players kill it) and melee “DPS” (dealing damage to an enemy). Every class should feel different to play. The Death Knight is primarily differentiated from other classes by its “rune” system.
  3. Core Mechanic: Runes.
  4. Class-defining abilities: For example, Death Grip, the only ability in the game that allows a player to pull an enemy towards them.
  5. Abilities for core roles: For example, switching between Blood and Frost Presence, depending on whether a DPS or tanking role is being undertaken.
  6. Abilities that reflect the class’s inspiration: For example, Death and Decay.
  7. Talents: These give players the ability to bias their strategies. For example, the Blood tree focuses on physical damage and “life”, the Frost tree focuses on frost damage and control, while the Unholy tree focuses on the “evil stuff” and minions. Talent trees are not intended to reflect specific roles [which is not the case for all classes].

Yet even the WoW Death Knight class example, which appears to be quite linear and structured, evolved considerably during development.

For example, the Death Knight’s runes were originally conceived as pretty free-floating icons within the User Interface. But they transpired to be hard to see. What really matters to players is “when does the ability become available”, so any button or icon has to clearly show “on” or “off” states. The second iteration, a class-specific blade-style border round the character’s portrait solved the first problem. However, then a new rune power mechanic was added (which charges up as the player uses other abilities), the redesigned blade-style border forced the runic power bar to appear where players were not expecting to see it. So players tended not to see it at all, forcing a third design to be developed.

Limiting Evolution

Core concepts within the game are unlikely to change, but specific details that are not yet “right” will continue to evolve, as this example from Tom Chilton (WoW’s lead designer) shows:

“We don’t plan to change the core role of classes. Instead we keep working on those [classes] that don’t work well enough.”

The semi-iterative design approach still has limits.

Sometimes design ideas evolve many times. Rob Pardo (vice president of game design) on Starcraft 2’s “Merc Haven”: “We love the look of the building, but haven’t figured out how to use it yet.” They have tried to figure it out 4 or 5 times.

The overall approach also starts to explain why Blizzard develops new games quite extensively before announcing or cancelling them (Gamasutra’s information suggests they cancel more than they release). Jay Wilson, lead designer of Diablo 3, responding to a question about why Blizzard had been silent on Diablo since 2001, thus:

“Development of Blizzard products is a long affair. […] It has to play and look awesome.”


Does this approach scale?

In a relatively few years, Blizzard have expanded from around 50 people, to over 2000 employees. They have 600 employees in their Paris offices alone. The human resource implications of that are terrifying, given the highly specialised knowledge and skill-set required: No surprise that Blizzard actively try and recruit the game’s players, who already have considerable background knowledge and enthusiasm.

While most of these people are customer-facing (community or support), and not developers, it still raises the question, who is in control of development?

Using WoWWiki’s figures for US WoW patch release dates, we can see that the typical time gap between patches for has gradually increased from earlier to more recent (higher numbered) patches. The dotted line shows the rough trend. Crudely, it is now taking at least twice as long to get a patch out than it did when WoW was first released:

World of Warcraft Patch Waits
Graph: World of Warcraft Patch Waits.

While each patch is unique, so cannot be compared directly, recent patches tend to contain a similar volume of content to older patches.

One possibility is that Blizzard have a “Man Month” problem. This concept was popularised by Fred Brooks’ book, The Mythical Man Month. It suggests that adding team members to a software project over time actually slows down the project, because the new hires spend so much time learning existing code, and everyone spends more time communicating. Logically MMOGs add a whole new dimension to the problem, because they are continually developed for many years: Inevitably developers will leave, and be replaced, even if the team size remains the same.

A related possibility is that managing or communicating through the “chaos” of continually evolving game design, simply takes longer as the project becomes bigger. Or at the extreme, most of the individual developers have no clue how their work fits into the rest of the game, because maintaining an overview becomes a job in itself.

Or it could reflect other unseen factors.

Shortly after WoW’s release, considerable effort was put into the “back-end”, to make game servers more stable. This work wasn’t clearly visible to players as new content, but probably sucked up a lot of development time. It is possible that now a lot (perhaps even most) development time is spent dealing with hacks, exploits and other cheats. Blizzard stated that dealing with cheats was a key priority (the comment related to Battle.Net, but we can assume applies generally). This work would also be largely unseen, but will slow down development of other content. (I can only assume that the decision to take legal action against the makers of Glider (a ‘bot that automates mundane aspects of play) was a rational long-term financial decision, where legal action is cheaper than developing coded solutions.)



Nobody can remember the last bad game Blizzard released. In fact, nobody can remember the last game that wasn’t released to popular acclaim followed by huge sales.

I suspect it is this legacy that dictates Blizzard’s design approach. Financial backers are prepared to risk pumping millions of dollars into the void, because the odds of producing a top-selling game are exceptionally good.

But if almost any other developer were to attempt the same approach, they’d be viewed a little like Derek Smart (who took almost 10 years to write a game that was essentially unplayable when released) – far too much risk, spread over far too many years. Which is why almost nobody except Blizzard can do what Blizzard do.

The big exceptions are in neighbouring markets, notably casual games, where the costs of producing games are relatively small. Perhaps it is another reason why the “next WoW” is more likely to come out of the casual gaming or social networking arena, than from the traditional “boxed” video game market.

Unless Blizzard do decide to go ahead with World of Starcraft, which Samwise Didier “announced” and then immediately cancelled during L70ETC L80ETC’s closing concert on Sunday evening (the band “levelled-up” during the show, from 70 to 80).

Technology and Casual Markets

Blizzard are already known for not always following prevailing industry trends in their use of technology. Almost 10 years after most of their peers moved from isometric style [edited – see comment by Itsnoteasy below] to full 3D environments, Blizzard’s latest game, Diablo 3, is still using an isometric style. Curiously, many of the most popular “games” use relatively primitive graphics – particularly those played heavily by children (from Habbo Hotel to many of the games for hand-helds/portables). Probably not the news the manufacturers of graphics cards want to hear.

Rob Pardo noted that, “Development on Mac’ historically was a great strategy for keeping system requirements low.” For World of Warcraft, they are expecting a lot of future growth to come from more casual audiences, simply because more people will have access to computers meeting the specifications for the game.

WoW was designed around the philosophy of “easy to learn, hard to master” from the start: Content becomes progressively harder, until only a tiny proportion of players can complete the final stages. Blizzard are aware that there is already a barrier to entry into the easiest dungeon content – it is simply too hard for some players. Themes of accessibility and approachability were constantly reiterated.

It remains unclear whether there will be any change of focus away from the high-end content, towards much more casual content. There is a clear desire to promote competitive e-sports, which require extremely challenging content or play styles.

It was revealed that WoW currently has “a very small team” that works on non-loot generating [I think those were the words used] aspects of gameplay, such as holiday events. So they “haven’t been able to do as much as they would like”. I presume “very small” is a euphemism for “we have someone who does that, sometimes”.

It will be interesting to see if they can broaden the player-base for their games, without loosing their e-sport stars to other games.

Questions, Questions

This article has tried to explain the semi-iterative approach Blizzard appear to use when designing their games. It shows how this approaches makes it almost impossible for them to release precise preview information until a game is about to be released. It also helps explain why a lot of answers read like this (with apologies to Bioware):

“[Question] What resources will Inscription (the new profession in WoW’s Wrath of the Lich King) use? [Statement] Well, we had this idea that it should use herbs [Conjecture] because ever since we eased the complexity of Alchemy last year, herbs aren’t being used so much; [Exploration] but we’ve only written 3 lines of code so far, [Contradiction] and the last one reads like the first two, so: [Weary resignation] I don’t know for sure, ask me again in December…”

Makes me wonder why they provide any pre-release detail at all. Do they really need the publicity?

As Tobold neatly illustrated (while I was preparing to post this article), understanding how and why Blizzard’s developers see their worlds is far more revealing that being told about detailed features.


8 thoughts on “Peeking Into Blizzard’s Development Process”

  1. Blizzard is an anomaly in the video game business. The main reason is that they are their own publisher. They don’t have to play the developer vs. publisher game and can focus on creating quality products that are released when they are ready. Check out Scott Cuthbertson’s (now an exec at 38 Studios) great introduction to The “Battle For Azeroth” book for more amplification on the Blizzard “secret”.

    As far as the Deathknight their first hero class, I didn’t see any explanation of how they rationalized the unlocking mechanics and the level 55 starting level. I continue to be a passionate critic of hero class as currently implemented and it will be interesting to see how this class impacts the MMO as whole.

    As far as Blizzard’s difficulty level, it’s not scaled very well at all between levels 1-70. In fact it’s far too easy as you can solo with ease without ever having to group with another person. The “hard to master” part of their design philosophy should start much sooner then the level cap. This has the effect of the majority of new MMO players reaching the level cap and feeling lost and ill prepared for the challenges that lie ahead in the “real” WoW which is raiding. Also many players find that they need to learn social skills in order to gain access to groups and guilds which are essential if their characters are to progress any further. Again Blizzard drops the ball with a very uneven and unscaled approach to increasing difficulty.

    Also thanks for the report on the revealing admission by Blizzard that they hardly have anyone focusing on non-combat/loot parts of their MMO such as events and role-playing. Certainly a company that takes in $520 million a year in profits could hire more people to help flesh out the weak areas of WoW.

    Great article. Please keep writing!

  2. Thanks for the reference. I was somewhat aware of Blizzard’s unique position in the industry. And the ability to hold convention-type events that attract 5,000+ people reconfirms their “superstar” status. Publishers aren’t too keen on developers becoming famous any more.

    The Death Knight unlocking mechanism was not discussed. The only reference was on the availability of Death Knights to all class: “The Lich King doesn’t discriminate – he likes them all!”

    My conclusions from writing guides to WoW (and other games), are that you can never make the first steps in a game easy enough. WoW does a pretty good job down at level 1: I’ve seen people who have never played a MMOG before get into WoW quickly. In contrast, the early dungeons can cause a lot of misery, particularly if you group with genuinely new players. About the only class to have gained any understanding of concepts like “threat” by level 15-20 is a Warlock (since it is so fundamental to playing the class). Most tanking classes get to experience it for the first time in dungeons – a poor setting to learn anything, for social reasons (everyone else just assumes you suck).

    I agree that the level cap causes a lot of problems. There isn’t a smooth transition into raiding, which is a completely different style of gameplay. The Burning Crusade’s attunement requirements seemed to be an attempt to control this transition, but ultimately created too much of a barrier to entry.

    As mentioned in the article, I’m intrigued as to know how Blizzard are organised internally. They could deliver content about 3 or 4 times quicker, and still not manage to keep all their players busy. As the graph shows, content additions seem to be slowing down, not speeding up. Big holes in content over time directly hurt their revenue, since players ultimately cancel their subscriptions (albeit with a significant time lag).

    Theory #1 is that their iterative approach simply can’t be made to “go faster”, because it relies on a relatively small group of veteran developers, with finite time. Add more people, and all they do is get in the way, because they don’t have the pre-requite level of understanding of what others are thinking.

    Theory #2 is that as Blizzard separates itself from the rest of the industry, there simply are no people with the correct skills and aptitude to recruit. If the games industry trains monkeys (because monkeys work fast, without question, for peanuts), where exactly do you find people who can think on their feet?

    So I think there is more to it than pure profitability.

    My current barometer for WoW’s casual game is mini-pets – companions that have no combat/gameplay role. If you look at the demographics for the people that love them most, you find almost half aged 35+, and most female: A classic casual market, that totally doesn’t reflect hardcore raiders. (Don’t read too much into the precise numbers for Warcraft Pets, because it is sampled and out by a factor of about 25 – but the proportions should be about right.)

    I suspect that last year Blizzard started doing some serious analysis of what players were doing in the game, and at this point they noticed there was a lot more casual play happening than the game was designed for. In the last few patches there has been a subtle shift towards more warm, fuzzy content. So maybe it is something they want to do more of. But I’m not sure they understand quite what they are doing yet.

  3. Good points about newbie content and how it needs to be gentle for new subscribers — the key to the health of any MMO. Blizzard has always been a master at creating an amazing first “15 minutes” (an industry term for the time you need to “hook” your player). I’ve read how they spent thousands of hours on the WoW newbie zones ensuring even the tiniest of details was perfect.

    One thing that concerns me is that Blizzard is starting devalue the leveling process in order to retain established subscribers. Established players can go a long way toward helping newbie players learn the ropes of a MMO. If they are not there then who will teach the new players?

    I too am confounded at Blizzard’s inability to release content any faster then they currently are despite the fact that they promised to release expansions once a year. I think both of your theories are essentially valid and correct.

    Here’s another one I’d like to propose and it relates to the size of an organizations and social groups. Malcolm Gladwell in his book The Tipping Point (chapter: The Power of Context part 2) talks about “The Rule of 150” which states that this is the maximum number of people that the average human brain can handle as far as managing social relationships. Throughout history 150 has been the optimum number for military units, villages and now corporations. He talks about how the company that manufactures Gore-Tex has used this very effectively in maintaining their success. (This is also a perfect number for MMO guild membership — but that’s another topic for another day).

    I would argue that Blizzard is the same way and probably has a core of 150 key people that produced the original WoW. They are probably very hesitant to add to the size of their team which they feel would impact the level of quality. In a previous blog article I believe I suggested that Blizzard create a live team and an expansion team (as SOE did with EverQuest).

    I read an interview with Jeff Kaplan the lead designer of WoW where he stated he was proud that *everyone* on the WoW team was solely focused on creating the expansion. Therefore it’s not very likely that they will do this given their commitment to quality and the size of their core team. However, the Gore corporation did the exact same thing; they split their company into teams of 150 and it worked splendidly. Blizzard would be wise to investigate this organizational approach.

    The lack of timely content and Blizzard’s addiction to polish will probably hurt them in the end as players grow tired of waiting. I liken this to building railroad tracks in front of a moving train. Blizzard can’t keep up and eventually the train will over take the tracks.

    Really great insights Tim! Keep up the good work.

  4. Interesting conversation.

    150 is the “Dunbar number”, which is a theoretical number of social connections our brains can manage effectively. However that doesn’t apply universally – creative and command groups are typically much smaller (that source suggests 12). As an aside, Christopher Allen has a lot on this related to MMOGs.

    Blizzard teams work across multiple games. For example, Samwise noted that the original Starcraft 2 art was too bright, because all the art people had got so used to creating WoW art. They’ve also made references to a “leadership team”, which seems to include all the well-known faces. Even if they have more than 150 developers in total (and I’m not sure about that, once QA and localisation is discounted), it doesn’t follow that they are all communicating with one another.

    I’ve listened to a chap from Gore speak. They certainly seem to have a very effective corporate culture, that does support creative activity. But then I’ve also heard people swear by breaking companies/operating units at 30, or just keeping a handful of people to do the creative work and outsourcing all the “doing stuff” to China.

    The whole process may be self-regulating: If the project is too ambitious, and you have so many employees that they can’t get it together, the result is poor and doesn’t sell, so less ambitious projects are attempted in future. Until fairly recently games were made by 30 people, and before that 3 people. It’s quite possible that nobody has stopped to figure out what works yet.

    Blizzard’s case isn’t unique. I’m sure Rockstar North (here in Edinburgh) could turn out a Grand Theft Auto every 6 months, and people would still buy it. They seem to work most hours in the day, but still don’t turn out games that fast.

    On a related note, Gamasutra just published an interview that reveals the decision to develop a new title is based heavily on what their employees would like to work on. Paul Sams says:

    “Our feeling is that if you’re going to have people put a number of years of their life, and they’re going to put their blood, sweat, and tears into the development of the game, they better believe in it, and want to play it, and it’s going to be a passion of theirs.”

    There’s a lot to be said for “doing what you like”. But it’s terribly limiting, since the people that make games are notoriously biased (to, would you believe, fairly deep, strategic PC games). Explains a lot about why they’ll miss certain markets completely.

  5. Just a quick note on something that really gets up my nose: Diablo 3 is not using isometric graphics; there’s no such thing. What I believe you’re referring to is isometric projection, but it’s not using that either. It’s using full 3D perspective like virtually every other 3D game released these days.

    Just because the camera’s fixed at a (0,30,45) angle doesn’t mean it’s isometric. The giveaway is that if you pick any shape in the gameplay video, it’s apparent length changes as the camera moves. If it was really isometric, vertical lines would always be perfectly vertical, nothing would get longer or shorter as the camera moves, etc.

    But otherwise a very interesting read; thanks for posting it. 🙂

  6. Just to add to my previous comments regarding the size of the Blizzard WoW development team, PC Gamer just published the transcript of an interview with Rob Pardo the VP of Design at Blizzard:

    PC Gamer: You have around 140 people working on WoW now…

    Rob Pardo: It is big… Every time we go to a new tier of team size it does cause us ripples for a time. We have to come up with a new way to build a creative and organisational structure for the team. Certainly, the creative process for a 140 person team is vastly different from a 20 person

    Looks like I was pretty accurate when I speculated on the size of the WoW dev team. Now we finally have some authoritative numbers from Pardo himself. 🙂

  7. Just a quick aside regarding Blizzard recruiting people. I’ve thought before of applying there. I’m qualified as a technical artist, and I know people personally who are more skilled than I am. Their location in Irvine, CA is a huge turnoff for working there. That’s ground zero for a lot of the housing mess. Cost of living is abysmal.

    Just sayin’… there’s more at work than Bliz being snooty.

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