7 design lessons from the history of Diablo

The Diablo series is one of the longest-running in games, spanning a whopping 27 years that culminated in the release of Diablo IV this month. Nothing lasts that long in entertainment without doing at least a few things right. And between the addicting click-clack of its hack-and-slash combat, its gothic tones and character classes, the unending quest for rare loot and armor, plus those late-night multiplayer sessions, there’s actually a lot Diablo excelled at. Despite, or perhaps because of, its long shelf life, there are lessons we can learn from its development that are still applicable today.

Here are some of those lessons, compiled from developer postmortems, guides, talks and blogs from the last three decades.

Diablo

The first Diablo game was released on PC on December 31, 1996, and was originally dreamed up by creator (and then high-schooler) David Brevik, who says that the series name was inspired by where he lived at the time—the base of Mt. Diablo. While it was initially conceived as a turn-based, single-player DOS claymation (!) game, the team would later take cues from the classic X-Com, copy-pasting its tiles to form the basis of Diablo’s isometric visual style, and adopting a real-time multiplayer format at Blizzard’s suggestion (a fateful, genre-defining decision they put to a studio vote, if you can believe it).

Taking a look at how Diablo came together also gives insight into the passion and enthusiasm of the small teams that built some of the industry’s earliest games. For example, twenty years after the original Diablo’s debut, Brevik did a postmortem at GDC 2016 that gave a good look at what went right and wrong in the course of the game’s development, including how they achieved Diablo’s dynamic gothic lighting, what missteps there were in designing the game’s floorplan, how the game evolved into its real-time format, the value of the game’s simple interface and character types (in part inspired by the pacing of Doom and NHL 95, of all things) and much more.

Brevik also details some of the principles that guided the development of the Diablo games, outlining values that would go on to become synonymous with Blizzard’s reputation for quality. One of those is to make your game as playable as possible as soon as you can. That’s where you will “find the fun,” he says, and begin ironing out anything that hinders the player’s enjoyment.

Because the team had a playable build “90% of the time,” they were able to test and iterate new features so quickly, rolling some out even in the weeks before the game’s release. This also allowed the devs to isolate the game’s most appealing aspect, the combat, and ensure every part of that experience, from the animations to the audio, supported a high level of stimulation (to that end, check out this relic from 2001, a Gamasutra Resource guide called Audio Content for Diablo and Diablo 2: Tools, Teams and Products, by Matt Uelmen).

Diablo was an industry-shaker not just because of its subject matter and playstyle, but because of what it brought along with it: the online multiplayer service Battle.net, which would transform how players would connect and interact with each other for the rest of the series.

At the time, Blizzard was understandably mum about how the system worked. In 1997, Blizzard’s Battle.net spokesperson Paul Sams did sit down with us for an interview in which he explained why they were producing the service and how the future of multiplayer was evolving. The article is a fascinating time capsule of a period when online gaming was still something of an uncertainty instead of an industry standard; at the time, it was unknown if online multiplayer services could “make money” on their own. This was a factor that Blizzard ignored in favor of the bigger picture. It’s a wild contrast to the gaming landscape of today, where it is universally understood that digital stores and portals are an integral cog in the machine.

(For more interesting tidbits on Diablo’s production, check out the full Diablo pitch document on creator David Brevik’s personal website.)

Diablo II

Following a brief period of burnout after the first game’s release, the Diablo team was ready to get back on the grind. Diablo II, released in 2000 and followed by the Lord of Destruction expansion in 2001, would make many improvements that would come to define later titles, introducing more character classes, complex skill trees, improvements to the color-tier loot system, and polished multiplayer (achieved by increasing server sizes and adding group-specific class skills.)

In 2000, Erich Schaefer posted a postmortem of the game in what was then the Gamasutra blog section. In it, he heavily reinforces how important it was that they made the game as playable as early as possible in the process. “If we hadn't experienced the core gameplay as early as we did, combat would have ended up feeling much more repetitive.” He also mentions that it enabled them to make changes to the game up until the very last second, some of which were very important to its success. “Only weeks away from scheduled beta testing, we scrapped our Act IV level layout schemes because they were just a bit too empty and similar. The last-minute fixes turned these levels into some of the best, befitting their climactic function.”

The article is another glimpse into how Blizzard’s famous design philosophies shaped the quality of the Diablo series; it’s long been known the publisher has used a “we’ll publish it when it’s ready” approach to release dates, but Schaefer confirms this, saying, “Blizzard's development process is designed to ensure that we make a great game. While our goal is to meet the milestones we set, our process, in terms of design and business, is structured to allow us to wait until the game is as good as it can be before we ship it.” While obviously, this is not a luxury that every, or even many, studios can afford (Schaefer also says, “Diablo II took more than 40 people and over three years, essentially because we made two or three games and pared them down to the best one.”), there is still perhaps a nugget of wisdom in the old school design sensibility of one of the adage’s accompanying pillars: “everyone contributes.” As noted by Schaefer on Diablo II and Brevik on the original Diablo, the team relied heavily on contributions from everyone on staff, no matter their job description.

The postmortem also highlights another of Blizzard’s design values: making their games easy to play. Says Schaefer, “We used what we call the ‘Mom test:’ could Mom figure this out without reading a manual? If we see new players struggling with how to sell items, we look at how they're trying to do it and make that way work too. We strove to make the interface as transparent as possible. You want to open a door? Left-click on it. Want to move to a target location? Left-click on it. Want to attack a monster, pick up an item, or talk to a non-player character? Well, you get the idea. It's amazing how many games have different controls and key combination[s] for all these actions when simpler is always better.”

To get more Diablo II development hindsight, you can watch David Brevik’s Diablo II postmortem from devcom 2020. A design diary he did for GameSpot, retrieved from Wayback Machine, also documents the transition between the first and second games, while this oral history given to USGamer by Brevik, as well as Max Schaefer and Erich Schaefer covers Diablo II. 

Diablo II: Resurrected

Blizzard’s eventual return to Diablo II in 2021 was defined by quality-of-life improvements that would not only update the game’s visuals but also add accessibility features, which Drew McCrory from Vicarious Visions (now a part of Blizzard) discussed in detail in his GDC 2022 talk Modern Accessibility in Diablo II: Resurrected, Because Hell Welcomes All (a write-up of which you can read here).

Perhaps the biggest lesson to take away from Diablo II: Resurrected is that when it comes to remasters or remakes, a careful balance has to be struck between new and legacy content. Players tolerate updates that bring an older game more in line with modern standards in certain areas, like chat functionality, and they expect improved, but not radically reimagined, visuals.

A broader overview of this is presented in Robert Gallerani’s Remastering a Classic: Diablo II Resurrected (paywalled) from GDC 2022, in which the principal designer breaks down their approach, not only in how different elements of the game were, or were not, updated but also the questions that guided the process: “Who is this for, and what do they want?” This should be the first thing you ask, he says, and not only should you let it guide the entire process but also, you should prioritize the answers before developing new features. For Diablo II: Resurrected, the core audience was considered passionate, hardcore players, and thus, features were designed with them primarily in mind.

If you’re a developer who is looking for more insight specific to your discipline, GDC 2022 was a treasure trove of design insight; here are some things you can check out for free with GDC Vault.

An Overview of the 'Diablo II: Resurrected' Renderer by Kevin Todisco

'Diablo 2: Resurrected': The Art Direction and Pipelines for Resurrecting Evil by Dustin King

Hair and Fur Rendering in Diablo II: Resurrected by Ace Stapp

Resurrecting a Classic: Bringing Diablo II into the Third Dimension by Kevin Todisco

Diablo III

Following the release of the original Diablo II: Lord of Destruction, it would be many years before another game would be released. By the time it went into production, a whole new team was in place, the core original designers having resigned with other employees in a dispute with Blizzard’s parent company, Vivendi, in 2003. A later postmortem by game director Jay Wilson arrived in 2013, which spoke on the making of Diablo III and elaborated on the design principles that guided its development.

As Vicarious Visions would later experience with Diablo II: Resurrected, much of the debate around Diablo III’s direction centered on creating the correct balance between legacy and new content, and how to take the reins on a series you did not personally create. The talk dissected the new team’s core design pillars, and whether or not they were able to achieve their goals, walking through several of those values and assessing the results. There are several points to take away from each, but one that comes up a few times is the idea that there were occasions where the team perhaps solved problems that didn’t actually exist, occasions where they could have left well enough alone.

As he puts it, “Don’t just solve problems. Assess your decisions. Weigh their impact.” Every design decision is going to have a negative side to consider. If you’re taking over a game series from a previous designer, there’s value in examining why the “cons” of their work were allowed to exist, and how the players felt about them. Later, when discussing the ill-fated auction house, he adds, “Don’t fix what isn’t broken,” but “don’t be afraid to take some chances to address major issues.” While, for example, Diablo III’s auction house ultimately created more problems than it solved, it was worth it to try addressing the off-site auction houses and account theft that proliferated with the prior game.

Wilson also warns against hiding behind game options, saying that giving the player too many can be a way to not commit to a single decision. While complexity can create depth, your game can be deep without requiring a player to pull out a spreadsheet and do math every time they change their character’s gear. Their goal was to keep the game approachable by making it easy to play, but make the player’s decisions more interesting by broadening the use of skills and dropping outdated features, like potions.

All this and much more is covered within the talk, which you can view for free over in the GDC Vault. You can also read more about some of the challenges of taking over art direction for an established series in our 2011 interview with Blizzard designer Leonard Boyarsky about the world design of Diablo III.

For advice more specific to your discipline, you can check out these other talks, for free, on GDC Vault or the GDC YouTube channel.

Through the Grinder: Refining Diablo III’s Game Systems by Wyatt Cheng

Technical Artist Bootcamp: The VFX of Diablo by Julian Love

Soundtracking Hell: The Music of Diablo III: Reaper of Souls by Russell Brower, Derek Duke, Neal Acree, and Joseph Lawrence

The Art of Diablo III by Christian Lichtner

Lessons and key takeaways

To summarize a few of the design takeaways from Diablo’s development:

Everyone contributes

The best ideas can come from honest feedback and candid suggestions from unexpected sources. The early days of Diablo and its sequel’s development thrived because of the energy and innovation that came from having everyone on the team play the game and submit feedback. Of course, it also helps if you hire gamers in the first place. As one of the original Blizzard co-founders, Allen Adham, told The Los Angeles Times in 2003, “That’s the secret to our success. We’re the target market. So what’s mysterious to other companies is just intuitive to us.”

Make it playable as soon as you can

The sooner the game is playable, the sooner you can “find the fun,” which means the sooner you can isolate and improve upon that experience. Multiple developers in the early part of the series cite their ability to get hands-on with the game as integral to the feedback and early implementation that defined its quality.

Focus on the moment-to-moment

Isolating and improving on the experience means focusing on the micro-moments and how they feel to the player. Says Brevik, “This for Diablo and Diablo II was, what does that combat feel like? How's it feel to move around the screen?” This helped fight the repetition of the game’s combat, which didn’t stray much out of rapid mouse clicking. Combining the games’ ease of play with attention to fine details created a pleasant sensory experience that combatted any potential monotony.

Nothing is sacred, nothing is ever done

Diablo, which was originally supposed to come out by Christmas 1996, famously missed that date, releasing a week later. But as (now former) Blizzard President Mike Morhaime would say in 2003, “Diablo missing Christmas was the best thing that could have happened to us. It proved that it was way more important to make a better game than it was to release a game before it’s ready.” From there evolved the philosophy that if something doesn’t feel right, change it; don’t waste time on sunk cost fallacy. Luckily, because Diablo II was playable “90% of the time”, bugs could be fixed and changes iterated quickly, allowing them to make those vital last-second improvements.

Ask, “Who is this for?”

From the series’ later games like Diablo II: Resurrected and Diablo III, we can also absorb lessons about finding the correct balance between fighting creative stagnation and honoring a game’s legacy. While the rules will be different depending on what sort of game you’re making (a remaster is different from a remake, for example), a good rule of thumb is a 70/30 split between new and old conventions.

Make it accessible

And from all the games, we can take note that “approachability” is key. From the series’ inception to the refinement of Diablo III’s skills and classes, to the quality of life updates of Diablo II: Resurrected, the goal of making the game easy to just pick up and play was a core value that boosted the series’ appeal.

Community

Over the years, our blog community has also lent its thoughts on the development of the Diablo series, including this excerpt from the book Stay Awhile and Listen: Book II – Heaven, Hell, and Secret Cow Levels called How StarCraft and Shower Epiphanies Influenced Diablo 2's Design by author David Craddock, which gives another inside look at some of the earliest days of the Diablo series. You can also read another excerpt in the post How Audio Design Enhances Diablo 2 by the same author. On the opinion side of thing is frequent Game Developer blog contributor Josh Bycer examining some of the tropes and storytelling methods of Diablo III in his piece The Plot Holes of Diablo 3, while psychologist Jamie Madigan takes cognitive function into consideration with his piece about the psychology of the loot of Diablo III.

And just for fun, here’s a throwback to that time Blizzard recreated the original Diablo in Diablo III to celebrate the series’ 20-year anniversary.