In early March, a data-savvy employee at the game studio Blizzard Entertainment started taking a hard look at rising number of U.S. COVID-19 cases, which then numbered in the low hundreds.

“We were able to do some math and say, looking at the China and Italy data, this is going to affect us very dramatically,” says J. Allen Brack, Blizzard’s president.

Within days, Blizzard, a unit of gaming giant Activision-Blizzard, asked groups of its designers, programmers, and other staff to work from home temporarily. They thought of it as a test, meant to refine the organization and infrastructure needed to keep creating video games, just in case things got really bad.

And of course, things got really bad.

“It was pretty damned fast,” says Blizzard executive John Hight. “We ran the test on Thursday [March 12]. A lot of people wound up staying home on Friday. By Monday, we’d made the decision, everyone’s going home, that’s it.”

It was a particularly serious decision for Hight. He’s executive producer for World of Warcraft, an online game with an estimated 4.8 million players, whose monthly subscription fees have helped make Warcraft one of the highest grossing game franchises in history.

WoW, as it’s often known, gets a major update every two years or so, adding new story and gameplay elements. And the latest World of Warcraft expansion, Shadowlands, was in the middle of development when COVID and the lockdowns hit.

The disruption would ultimately create a nightmare for Hight and his team of hundreds of programmers, artists, and writers. After first announcing the game would be released on October 27, Blizzard was forced delay the date to November 23.

But the difficult decision to delay Shadowlands, and the hurdles that Blizzard cleared along the way, came with invaluable lessons. Here are the most important takeaways Brack and Hight shared with Fortune.

The global advantage

Before it was clear what was coming to the U.S., Blizzard’s global reach gave it an even earlier warning.

“We have several offices in Asia, and an office in China,” says Brack. “So we were able to see, from our own employees, what was happening in China starting in February. And we saw the China response, which was to send everybody home.”

That, says Brack, gave company leaders a game plan when cases started showing up in the U.S. “We were able to prepare a little bit ahead of, I think, most companies.”

Office space is the place

“First, Mea culpa. This was my screwup,” says Hight of the Shadowlands delay, which inevitably disappointed fans.

But of course, much larger forces were really to blame. In particular, working from home made it more difficult to do the kind of refining needed to make a game – or any product – truly great. That didn’t become obvious until the original October 27 release date got closer.

“Functionally, everything was done” by early fall, says Hight. “But there were things that were confusing, the bug count was still kind of high … That polishing and tuning was something that we hadn’t done enough of before we made the decision to announce the [October] date.”

Getting those last few details right, Hight says, would have been a lot easier with the whole team in one place.

“Especially on the design side of the game, we [normally] work in a fairly open space. The combat designers sit together, the level designers sit together. There’s a sharing of ideas. When you’re in a room together, it’s very natural to have that communication … If we were all in a room together and playing, we could have said, ‘Hey, I don’t really get this.’”

Nerds (with high-end home PCs) rule

Blizzard had an edge when it came to the technical infrastructure of working from home. After years of collaboration between teams worldwide, infrastructure for remote access to things like email and the corporate intranet was basically ready to go. So were tools to share the huge video and texture files that make up modern games.

And getting designers and testers the hardware they needed wasn’t much of a problem either: “As a company of gamers,” says Brack, “There’s a lot of high-end hardware that our employees have at home already.”

Quiet staffers aren’t necessarily happy staffers

Running a company full of gamers does have its downsides.

“A lot of folks are super creative, says Hight of his team, “but they’re also kind of introverted.”

That became a bigger issue with the transition to working from home. “In the world where we’re all talking through webcams, in our own space, it’s natural for humans to kind of hole up.” Some team members, Hight says, felt “reluctant to ring somebody up and interrupt their home life to ask a question or share an idea. It took us a while to overcome that.”

Blizzard’s managers had to do more than usual to keep those channels open.

“You just check in on people,” says Hight. “Hey, how are you doing? How’s the family? They don’t necessarily think to get out and push themselves on others, but that also doesn’t mean they want to be neglected.”

The mission is the answer

World of Warcraft is meant to be enjoyed together, with players from around the world forming groups to delve into dungeons and take down fearsome enemies. That social element helps make it an ideal form of pandemic entertainment.

“That helped us,” says Hight, “Knowing that we were doing something that was super important to people who needed entertainment during this time, needed some connection to the outside world.”

“Every day, the news was getting more dire. Answers weren’t really there … Having purpose during all of this, I think, allowed us to carry on.”