Some time around last Christmas, Michael Condrey, the co-founder of Sledgehammer Games, huddled in a foxhole in Hürtgen forest, on the border of Germany and Belgium. In a nearby foxhole, buried under five feet of snow, Condrey's fellow co-founder, Glen Schofield, was dreaming of the heated van they'd left on the side of the highway three hours earlier.

The only one who seemed to be enjoying himself was Condrey and Schofield's guide, Martin Morgan, a war historian who leads battlefield tours around Europe. He was examining a squat, pyramid-like structure made of concrete--what was left of an entire row of so-called "dragon's teeth," fortifications made by soldiers to stop advancing tanks.

Condrey and Schofield had hired Morgan to bring them here, to the site of one of the biggest clashes of WWII, The Battle of Hürtgen Forest. Sledgehammer had just started work on a new Call of Duty game that would, for the first time in a decade, return to a WWII setting, and Condrey and Schofield wanted to see the battlefields for themselves. They wanted to sit in the same foxholes where hundreds of young Allied and German soldiers had sat during the winter of 1944, braving blizzards, hunger, and the constant fear of death. They wanted to walk on the same ground as Allied soldiers during the liberation of Paris, drive the same tanks, fire the same weapons. They wanted to come as close as possible to understanding a soldier's experience of what Condrey calls "the last great war."

"After three hours, I was ready to get in the car and turn the heater on," Condrey said later. "It really made us committed to honoring what we came to realize was an incredible sacrifice."

Condrey and Schofield, both in their mid-40s, first met while working together at EA's Visceral Games. They created 2008's critically acclaimed Dead Space before leaving to start Sledgehammer in 2009. Activision acquired the studio later the same year after the pair successfully pitched a third-person Call of Duty spinoff title that would attempt to mirror the success of Dead Space. That game never happened--the Jason West/Vince Zampella lawsuit kicked off, and with development on Modern Warfare 3 in potential jeopardy, Activision asked Sledgehammer to join forces with what was left of Infinity Ward to finish the game.

Modern Warfare 3 was a commercial success and gave Condrey and Schofield the freedom to pretty much do whatever they wanted; a few years later, Activision gave them the reins to the franchise's first sci-fi instalment, Call of Duty: Advanced Warfare.

Michael Condrey (left) and Martin Morgan surveying foxholes occupied by 101st Airborne during Battle of the Bulge, in Bois Jacques, part of the Ardennes Forest just outside Foy, Belgium.

When it came time to work on a new Call of Duty, Sledgehammer and Activision asked themselves where they wanted to see the franchise go--as fans, rather than developers. Back to where it all began seemed like the right answer, particularly in light of Hollywood's recent fascination with WWII, from David Ayer's Fury in 2014 to Hacksaw Ridge, Allied, and Christopher Nolan's Dunkirk earlier this year. "When you think about it, [before these films], Saving Private Ryan was the last great WWII film, and that was 20 years ago," Condrey told me recently. "That's like a whole generation ago. We saw an opportunity to reenergize the cause in a place where films and games haven't been for a while."

We were sitting in a boardroom adjoining Condrey and Schofield's office, at Sledgehammer's headquarters in Foster City, California. The decade or so Condrey and Schofield have spent working together has lent them an endearing, Odd Couple-like vibe: Condrey is quiet and methodical, a master of corporate jargon, while Schofield is loud and unrehearsed.

The studio is in the middle of an expansion--Condrey and Schofield recently took over the floor above them, and construction on new offices, meeting rooms, and a lobby is underway. (The decor says more accountant's office than video game studio; the one indulgence seems to be a Crayola-blue slide that connects the first and second floors, which employees regularly attempt to master while holding full cups of coffee, to varying degrees of success.)

Schofield grew up hearing stories of his grandfather, who served in WWII, and his uncle, who served in Vietnam. He still keeps his grandfather's war medals in a glass case in his office. There's a Bronze Star and a Purple Heart, which, as the story goes, Schofield's grandfather won for ambushing a German machine gun patrol while fighting in Italy. He lost his leg in the process, but he refused to talk about it. It fell on Schofield's father to retell the stories, and he did, often.

Dragon’s Teeth from an area on the Siegfried Line near Hollerath, Germany.

Shortly after development on WWII began, Schofield's father died. Suddenly, it was Schofield's turn to step into the role of storyteller. "We realized we need to keep telling these stories so the world doesn't forget what happened--and so it doesn't happen again," Condrey said.

Schofield began writing to different US regiments and divisions: the 34th, the 1st, the 101st. Most responded enthusiastically, sharing stories, details, and ideologies. "The first thing you realize when you talk to veterans is that they absolutely do not consider themselves heroes," Condrey said. Those conversations eventually helped shaped the game's main narrative, which follows a young soldier deployed to the battlefields of Europe with the US Army's 16th Infantry Regiment.

Typically, Call of Duty characters are gruff, hardass types--Captain John Price, for example, who pops up in all the Modern Warfare titles, is a member of the British Special Air Service and toughened POW who served time in a Russian prison. Captain John "Soap" MacTavish, another favorite, is an expert in disabling nuclear missiles and seems to spend half of the series mortally wounded. By contrast, WWII's main protagonist is as green as they come: 19-year-old private Ronald "Red" Daniels--Schofield named Daniels after his father--who has never been outside of Texas before.

Daniels won't be able to solve every problem with a gun, either. "There are absolutely stretches of it in different levels where it's just sheerly about survival," Bret Robbins, the creative director at Sledgehammer, told me. "We didn't want it to feel exclusively, you know, 'If I just shoot enough people I can get through this experience.' Because these guys weren't professional soldiers, remember that. They ended up becoming superhuman purely because of the things they had to go through."

One of the game's most dramatic moments, according to Robbins, happens when one soldier punches another. "I mean, this would be a trivial matter in a normal Call of Duty game, right? But here, it's actually a really charged moment."

After figuring out a rough narrative for the main campaign, Condrey hunted for an academic specializing in WWII history. A friend recommended the historian, Morgan. The 48-year-old worked with the late Stephen Ambrose, author of the New York Times bestseller Band of Brothers, and consulted on the HBO mini-series The Pacific. Morgan's particular academic interest is in what he calls memorialization--the way pop culture representations of war can sometimes introduce factual errors that linger in the public consciousness.

Take Saving Private Ryan, for example. The film, which came out in 1998, renewed interest in WWII by reaching levels of authenticity that no war film ever had before. But it also simultaneously introduced certain inaccuracies--like the idea that D-Day was actually that intensely violent the whole time. "The attraction to the time and place of greatest gratuitous violence has made it difficult to convince people that D-Day on Omaha Beach, in some places, did not descend into hopeless chaos," Morgan told me.

We talked about making a game that could possibly teach people why we should never have this happen again. Michael Condrey, Sledgehammer Games

Which is to say that Morgan is a stickler for details. He began advising Condrey and Schofield on everything from uniforms to weapons. He invited them to the National WWII Museum in New Orleans so they could sit inside German tanks. The studio sent the entire sound design department to Louisiana, where Morgan lives, to record audio capture of Morgan's World War II weapons, while the art department got access to Morgan's impressive stockpile of original archival WWII photos.

But Condrey and Schofield wanted to go further. "Some of these guys walked across France with a 60-pound backpack, a 10-pound gun, wondering where their next meal was going to be," Schofield told me. "What does that feel like?"

They asked Morgan to show them.

The original idea was to follow in the fictional Red Daniels' footsteps, from Normandy through Luxembourg, Belgium and Germany. Morgan coordinated everything, including necessary pit stops: the Luxembourg American Cemetery and Memorial, in which some 5,076 American service members are buried, most of whom died during the Battle of the Bulge; the Holocaust memorial in Berlin; a burned-out church in Where, France that German troops set on fire after ordering everyone in the village to get inside.

"If you think about a lake, and are asked to describe it, most people would describe it as something like 'blue water'," Condrey said, explaining he and Schofield’s version of 'boots on the ground'. "But if you actually visit a lake, you'll find the water is rarely blue--it might be blue-green, or a little bit gray, or maybe even black. So it's this idea of what you think something is and what it actually is--and you can never know until you see something for yourself."

Detail of bullet damage on a house in Foy, Belgium. This damage was produced during the 506th Parachute Infantry Regiment, 101st Airborne Division attack on German forces occupying the town on January 13, 1945.

Morgan knew exactly where to take them. "We were driving around somewhere in Europe, I can't even remember where now, and we came around the corner of this road and there's this giant tank just hanging out in the middle of nowhere," Schofield said. "And it's because it's so big that no one could actually get it down the hill, so it's just been sitting there since the war. And I'm thinking surely we should be able to move that nowadays with cranes or whatever. And Marty's like, no, this thing is over 60 tonnes. And we get up close to it and there's a giant bomb stuck inside it--it's a German tank that was hit with an American shell and the tank was so tough that not even the shell could get through. It really drove the point home just how strong some of the German equipment was, and why they were such great engineers."

The foxholes and dragon's teeth from Hürtgen forest both made it into the game. Condrey and Schofield also designed a sequence featuring what can only be described as exploding trees. The density of the forest meant a lot of the shells ended up hitting trees, not soldiers--which could prove even more fatal. "You got these huge chunks of wood flying a thousand miles an hour into people," Robbins said. "More people died from shrapnel from the trees than from the actual shells themselves."

German Pillbox, part of the German Westwall, Wallendorf, Germany (along the Luxembourg/German border).

There are thousands of photos in Sledgehammer's archives from each of these trips, many of them trying to capture the smallest of details: rust on an old bomb shelter in the middle of Luxembourg (that's since been turned into a bus stop); bullet holes in a wall in a village in Belgium; an old church in a village in France. Most were taken by Sledgehammer's art director, Joseph Salud, whose task was to document the miniscule visual details of each environment. He went to Normandy beach on June 6--the anniversary of D-Day--to capture everything from the color of the sky to the size of the waves as they might have been on that day in 1944.

When Condrey and Salud visited Gibraltar, in Spain, which features in one of the game's multiplayer maps, they realized they'd put one of the city's most iconic buildings, The Moorish Castle, completely at the wrong end of the map. "It was 180 degrees from where it was supposed to be, and we wouldn't have known that unless we'd actually gone to see it," Condrey said. (They also encountered the Barbary macaques, a species of tailless monkeys that make an appearance in the game after a friendly one made off with Condrey's backpack.)

Salud took notes from The Revenant, which director Alejandro G. Iñárritu shot using only natural lighting in remote locations around Canada, the US, and Argentina. "I loved how [Iñárritu] was able to capture the feeling of the weather--the mood and emotion in the film all flowed from that." To try and imitate the same process, he used photogrammetry--photographing in realistic lighting conditions and then extracting the finer data points from the photographs to make an accurate digital 3D rendition. "You could take a snapshot of any one of our screens and you'd still be hard-pressed to tell it's not a photo," Schofield boasted.

Detail of Panzer V Panther Tread in Houfflaize, Belgium .

Probably the best way to test this is to look for piles of rubble in the game. Salud spent half a day photographing one particular pile of rubble in the crumbling village of Oradour-sur-Glane, in France, whose 642 inhabitants were massacred by Nazi SS soldiers in June 1944. After the war, French leader Charles De Gaulle ordered the destroyed village be kept in its original state as a memorial. "Prior to coming here, the rubble we had in the game was just, you know, generic rubble--bricks and stuff," Salud told me. "But actually, in real life it's not generic is it? There are things buried beneath it: bits of cars, furniture, children's toys. It humanizes the whole experience."

Even the game's famed Zombie mode has elements of historical accuracy, thanks in large part to the WWII history museum in Luxembourg, which contains a hefty collection of Nazi oddities and medical equipment. The photos brought back by Scott Whitney, the game's narrative director, are the stuff of nightmares: oversized syringes, surgical spreaders, Nazi chainsaws.

There's also the fact that Hitler himself was eternally obsessed with the occult, hoping he'd stumble on proof of a master race. "These crazy f***ers began pursuing archeological digs to try and prove these theories," Jon Horsley, the lead on WWII's Zombies mode, told me. According to Horsley, who has been intensely studying Nazi relics, the Zombie story will revolve around the myth of Barbarossa, popularized by the Brothers Grimm, which centers on an undead German emperor who sleeps beneath a mountain, waiting to be awoken. "So yes, it's still Zombies--but with a purpose," he said.

More often than not, games of WWII's size and budget tend to be binary in their depiction of good and evil, with little in the way of grey areas. After returning from Europe, Condrey and Schofield realized they'd have to take a different approach. "There's humanity on both sides," Condrey told me. "So you'll see the best and the worst of both the Allies and the Germans."

This realization also went some way to helping the studio figure out how to deal with the darkest aspect of WWII in a game whose ultimate purpose is entertainment. Condrey and Schofield didn't want to talk about the extent that the events of the Holocaust will be covered in the game--other than to say it will be covered--but Morgan did tell me the topic is too important to be dealt with superficially. "When it comes to Holocaust and genocide education, we are overexposed and undereducated," he said.

"It didn't feel like it would've been a complete picture or very honest game if we hadn't addressed some of that," Robbins told me later. "We definitely go to a dark place at times, and it just felt very important to us to show that in some form that these events happened."

The beaches of Normandy, today.

Presenting the events of the Holocaust without being overly didactic certainly carries weight, particularly in light of recent events. I visited Sledgehammer a few weeks after white supremacists and neo-Nazis marched across Charlottesville, Virginia, carrying torches and guns while chanting, "Jews will not replace us." At a time when games have a wider reach in popular culture than ever before, the medium seems perfectly positioned to participate in the wider discourse. "We need to address the subject of what a destructive ideology can do when it takes control in a country where democracy has been undermined and destroyed," Morgan, the historian, said.

Condrey and Schofield seemed reluctant to go that far. Condrey did offer this, however: "I've worked on a lot of games I'm really proud of," Condrey said. "None have carried the historical weight and meaning that this one has."

"We talked about making a game that could possibly teach people why we should never have this happen again," Schofield said. "Can we really do that in the game? I don't know, but you've got to have a higher goal when you're working on something like this."