Terraform: The Making of Doom 64

JOHN ROMERO'S EYES FOLLOWED THE engineer as he placed his cargo on the pool table. Their visitor hailed from Sega, and the item he placed on id Software's pool table was a motherboard, still in prototype stage. When completed, it would power the 32X, Sega's add-on hardware that would evolve the Genesis console from a 16-bit dinosaur into a 32-bit giant.

Romero and the rest of id Software's small team gathered 'round as the engineer set a monitor on the felt surface, plugged the prototype into it, and powered it on. Code filled the scream. Romero recognized some of it. So did John Carmack, fellow co-founder of id. It was a port of Doom, or would be. At that moment, it was a work in progress. To convert the game, Sega needed help figuring out how Doom's code should be modified to run on the 32X.

"Carmack got as much information out of him as he could give about the processor," Romero said, "and then gave the engineer suggestions to make the blitter"—a circuit that rapidly modifies and moves data in memory—"go faster. That's how Sega got the 32X version running."

Staging Area

Sega's port turned out as well as the guys at id expected: Not very well at all. The 32X depended on the Genesis to run, and the Genesis was well past its expiration date. Concessions had to be made. Textures were stripped away. Pixels viewed from medium to far range, such as items and enemies in the distance, were blurred, indistinguishable unless viewed up-close. Choppy performance forced Sega's team to surround the playfield—the window into the game—with a border; their solution lightened the processor's load, but made the already-indistinct graphics even harder to see. Enemy sprites were hacked to pieces until only the front side remained. Consequently, demons always faced players, which meant they could not be ambushed or made to fight one another, staples of the experience playing on PC.

Worse, Sega dropped one-third of Doom's levels, including its memorable Cyberdemon and Spider Mastermind bosses, due to technical constraints. The result was a game that seemed to fizzle out when, in fact, players should have had another nine levels to play. "It didn't have a very large [on-screen] view. It was very under-powered," Romero added.

Sega's 32X port proved to be the rule of Doom ports, rather than the exception. No other console platform compared to the more versatile PC. The Super Nintendo version made by veteran SNES development studio Sculptured Software played even choppier than the 32X version, and the Atari Jaguar adaptation, developed in-house at id, was only slightly sharper in terms of graphics.

Id's track record with ports was hit or miss. The team had handled only one other port in-house, Wolfenstein 3D on the Super Nintendo. That gig had almost been a disaster. In 1993, id's biz manager, Jay Wilbur, had received a phone call from Imagineer, a publisher in Japan who promised a $100,000 advance if id's team would bring Wolfenstein 3D to the SNES.

The guys accepted the job, cashed the check, and promptly forgot all about Wolfenstein's conversion. They had moved on to Doom, and were happy entrenched in developing its engine, level-editing program, and game design.

"Seven or eight months had passed," Romero recalled. "Imagineer came back to Jay and said, 'Is the Wolfenstein 3D port done yet?' Jay said, 'Oh. Shit.' He ran to us and said, 'Guys, what's the story with the port?' We said, 'Oh. Fuck.'"

Id had no intention of handling the port in-house. No one knew the ins and outs of programming for the SNES, and Doom took top priority. So they had hired a programmer well-versed in Nintendo's 16-bit console for the job. Time had passed without word of his progress. With Imagineer breathing down their necks and Doom's design still coming together, they phoned him at home, but received no answer. They called again. And again. Every time, his phone rang and rang.

At last, his wife picked up, and explained that her husband could not complete his work. "He's sick," she said, and hung up.

"Now, we were busy making Doom at that point," Romero continued. "We stopped all work on Doom and had to learn how to program a Super Nintendo. Learn about the graphics: what format they're in, the layout of the screen, all that shit."

In a matter of weeks, the guys learned how to code on Super Nintendo and sent a respectable port off to Imagineer. It looked and played well enough, restrained more by Nintendo's strict family-friendly policies than technical limitations.

"Nintendo told us that we couldn't have the police dogs on the levels, because killing dogs was mean, I guess," explained Sandy Petersen, id's newest level designer hired on to help Romero crank out maps for Doom, and who switched gears to the SNES port of Wolfenstein to get the game finished on time. "So we replaced all the dog sprites with giant rats. Apparently it was okay to kill rats—and people!—but not dogs."

Nintendo also requested—demanded—that Wolfenstein 3D's blood no longer be colored red. "When you shoot someone in Wolfenstein there is a splatter of blood," said Petersen. "We changed the blood sprites to white. Every time you shot someone in Wolfenstein, it kind of looked like they were spitting or jizzing all over."

"We did all this shit, and it took us three weeks," Romero said.

Porting Doom to Jaguar had been more of a passion project for John Carmack, who expressed interest in tinkering with the console's 64-bit hardware. (In truth, the Jaguar ran on a 32-bit processor; only its blitter, a chip able to manipulate data quickly, and object processor, a component that reads graphical data and sends it to the screen, were 64-bit.) After Doom released on Jaguar released, the id guys moved on from ports. If another company wanted to adapt Doom or any other title to another gaming system, they were free to do so, provided id got to keep an eye on the project to ensure it hit an acceptable level of quality.

There was only one exception.

"Nintendo was sensitive about a number of things in the game that we felt were necessary," Jay Wilbur said regarding Wolfenstein 3D's conversion to SNES. "The result of the experience at that time was us opting not to do another game with Nintendo while these policies were in place. Something I told [Nintendo of America counsel] Howard Lincoln personally as I recounted our frustration of the development process."

Shortly after Doom shipped in 1993, Wilbur received a call from Byron Cook, co-founder of Tradewest in 1985 along with his father, Leland Cook, and their business partner, John Rowe. Tradewest started as a manufacturer of coin-op games for developers such as SNK, then pivoted to porting arcade games to home systems. In the spring of '94, coin-op studio Williams Electronics Games, owner of Bally/Midway, acquired Tradewest, and re-branded the studio as Williams Entertainment, Inc, which became Midway Home Entertainment in 1996.

Rowe and the Cooks operated Midway Home Entertainment (still known as Williams Entertainment at that time), and scouted for new businesses opportunities. One, a partnership with id Software, seemed promising. Byron had kept in touch with Wilbur during the transition from Tradewest to Williams Entertainment. During one conversation, he broached the subject of making a Doom game for Nintendo's upcoming Ultra 64 console. "I recounted our experience with Nintendo on Wolf3D and Byron set out to pave a path to make it happen," Wilbur said.

Tech Center

JOHN ROMERO AND JAY WILBUR cruised along Highway 45 toward Houston. Two hours into the drive, they took an exit and followed their route to the parking lot of Midway Home Entertainment. Romero was all grins and nervous energy as they entered the lobby.

"Midway had been around for decades. We respected Midway," he said. "Other companies that worked on Doom ports, we didn't know them that well. But Midway was known as a quality company back then."

Byron rolled out the red carpet for their visitors. Romero and Wilbur met Michael Gottlieb, a veteran producer, director, photographer, and one of Midway's most well-known producers. They were especially impressed with Aaron Seeler, a programmer and one of the many self-described "rabid" Doom fans at the company. Seeler regaled them with stories of staying late into the night to play deathmatch.

Wilbur and Byron solidified the terms of their deal. Nintendo was generating hype for its Ultra 64 console, but had offered few concrete details on what the embryonic hardware would be. While they waited for that information to solidify, Byron suggested an alternative project: A port of Doom and Doom 2 to Sony PlayStation.

"The PSX version was a two-for-one byproduct of the N64 deal," explained Aaron Seeler, "and served as a development base for all the research-and-development tech and tools we would need to bring up for the N64, which was not anywhere close to specs or silicon. All the N64's capabilities were wild guessing."

PlayStation was still relatively new hardware when Midway and id struck their deal. Seeler, who would lead programming efforts on Doom's conversion, had no experience with 3D hardware or graphics. John Carmack offered to give him a crash course, so Seeler relocated to id and moved into an office down the hall from Carmack's.

"I learned 3D and the graphics pipeline from John," he recalled. "The PSX version was the harder technical challenge [compared to Nintendo 64]."

Seeler read through Doom's source code. He marveled at how clean and layered Carmack had structured it; that made it easier for Seeler to complete his task. Doom couldn't run on PSX as it was written. Seeler's mission was to rewrite portions of it so the PSX's triangle-based hardware could process graphics and throw them onto the screen.

Two major challenges stood between Seeler and his goal. First, he needed to develop a perspective-correct rasterizer. A rasterizer converts an image made from shapes—usually triangles, the base shape of three-dimensional objects—into a series of pixels and lines, collectively called a raster image. "Perspective-correct" rasterization orients those images so they grow larger as players move closer to them, and shrink as players move further away. In essence, a rasterizer needs to know what players see, and when they should see it.

Seeler's second challenge was to ensure that Doom ran at a decent frame rate. The choppy performance and sluggish controls of the SNES and 32X ports were not an option.

Seeler began by working with a hybrid of Doom's source code and Carmack's conversion for Jaguar. Then he set about writing tools: a brand-new editor for Midway's designers to use to modify maps from Doom and Doom 2, as well as create a few of their own; routines to process and display textures; and other essentials. As he built tools, he cobbled together E1M1—episode 1, mission 1, the first level of Doom—and showed it to Carmack to get feedback.

Carmack was unimpressed. PlayStation's hardware was capable of more than Seeler's prototype was showing. Seeler kept experimenting and came up with techniques that would differentiate Doom's PSX port. Sector lighting and color depth, for instance, could be used to create gradients of lighting far richer than those on the PC. Lighting could be set to fade in and out, setting a much creepier atmosphere. Alpha blending could render certain objects transparent.

Seeler added more functionality to his level editor and sent the update to Danny Lewis, Randy Estrella, and Timothy Heydelaar, the designers in charge of reworking levels from the PC version of Doom so they would run on PSX. "We did a bit of iterations and tweaking to get the features they proposed, and they took off with it," Seeler remembered. "They had ElM1 amplified straight off."

Seeler showed a new demo to Carmack. He conferred with the other id guys, and came back with a thumbs-up.

"Properly done, it really enhanced the gameplay and gave the PSX version its console punch," Seeler continued.

Now that the Midway team had momentum, Doom PSX's features flew into place. Skyboxes, the region above a level's walls, no longer had to be still images. Artists created animated skies such as dancing walls of flame for maps set in Hell. Geometry was modified so maps to accommodate PlayStation's hardware, with maps in Doom's original three episodes (Knee-Deep in the Dead, The Shores of Hell, and Inferno) undergoing the most significant alterations, many of which had been used to squeeze the game onto Atari Jaguar.

Midway' designers restructured Doom—which included The Ultimate Doom's fourth episode, Thy Flesh Consumed—in a way that appealed to veteran Doom players. Rather than breaking the game into discrete episodes, a marketing decision for the PC version that allowed id to give away the first episode for free and entice consumers to buy the full game, Doom's four episodes were sewed into a contiguous experience, like Doom 2. No longer would players start each episode with only a pistol and 100 health; their status carried from level to level. A few maps between episodes three and four had to be removed due to the complexity of their size and geometry; Midway made up for the omissions by crafting several new stages that bridged players' journey into episode four.

Nightmare, an extreme difficulty level in which enemies attacked and moved twice as fast, and returned to life after being killed, was removed. Midway came up with something better. Playing on Ultra-Violence, Doom PSX's highest difficulty, seeded monsters from Doom 2 into Doom's maps. The goal was not to overwhelm players, but to change encounters just enough so players familiar with Doom would have to rethink some of their strategies. Commandos, corpulent soldiers that drop chainguns on death, could be found patrolling certain areas. The Revenant, a skeleton armed with heat-seeking missiles and a mean right hook, stalked later levels to ambush players.

Doom PSX's color techniques allowed designers to come up with new enemies. The first, a darker version of Doom's Spectre, withstood twice as much damage and inflicted more pain. The second was a transparent "Pinky" demon engineered more to show off the PlayStation's hardware than to alter gameplay.

Where the game shined, however, was its atmosphere. Doom PSX flipped the script on Doom's action-horror motifs to horror-action. Seeler and the designers reworked rooms and hallways to add light that faded in and out. The visuals were scary enough, but its audio made the game utterly terrifying.

Bobby Prince, composer for Doom and Doom 2, had a unique deal with id. They had given him the rights to his creations, which meant he received royalties for any port that utilized his sound effects and music. Midway didn't want to pay those royalties, so managers assigned Aubrey Hodges, one of the studio's composers, to record a new soundscape for the PSX port.

Almost by accident, Hodges discovered that the sounds he leaned toward would have worked perfectly in a horror movie. Using a combination of instruments and recording hardware and software, he laid down a series of ambient tracks that burrowed under players' skin as they played. Doom PSX was still Doom. There were still dozens of monsters to shoot and lots of ammunition scattered around maps. But the phlegmy grunts and growls of Hodges' audio, combined with the eerie, unnerving tracks that played as they explored, made players feel like they had set foot in a game that was both familiar to and unique from the one id Software had released on PC in 1993.

Doom PSX arrived in stores on November 16, 1995, within the first year of the PlayStation's availability in Japan and the United States. The team at Midway were pleased with their creation and its sales, as were the guys at id. "For PlayStation, we decided to give Midway creative license," Romero said. "They did a really great job on the audio and level design. We were very happy with it."

Midway followed Doom with a PlayStation port of Final Doom, composed of two 32-map episodes, in 1996. With the ports selling well, Aaron Seeler took stock of his tools and looked ahead to the next project: A completely unique, from-the-ground-up Doom experience unlike any that had come before it.

"I was working on PSX as a head start of code and tools into N64, as the art production for N64 had longer lead times," said Seeler. "The PSX was the R&D testbed of what we were going to be ramping up in N64."

Dark Citadel

NINTENDO'S NOMENCLATURE FOR SUPER NES was easy to grasp. If a developer ran short of ideas, they could just spit out a title and stick "Super" in front of it. Super Star Wars, Super Punch-Out, Super Bomberman, Super Castlevania IV, Super Metroid.

Nintendo 64, renamed from Ultra 64 after its 64-bit architecture, followed a similar syntax: Title of Game, followed by "64." Super Mario 64, Pilotwings 64, Bass Hunter 64, and so on. Often, titles bearing the "64" label were iterative sequels to two-dimensional games taking the logical step into the third dimension, or ports of existing games, such as Duke Nukem 3D on PC becoming Duke Nukem 64. Midway and id Software were determined for Doom 64 to be the exception to the rule.

"They could do what they wanted," explained John Romero, co-founder of id, regarding the Doom 64 team at Midway. "Make it a different story, not even on the same narrative path. That's what they did. They wrote a whole new engine, completely new levels, higher-res graphics for characters."

There were pragmatic reasons for adding "64" onto the end of Midway's 64-bit Doom game. "The '64' was a concession to all the parties involved," admitted Midway's Aaron Seeler, programmer on the PlayStation port of Doom and the forthcoming Doom 64. "That was truly the only thing marketing could get all the IP holders to agree on."

Id Software set ground rules for a title. First, and most obvious, the game had to have "Doom" in the title. That was their brand. Second, "Doom 3" was off the table. Although id had moved on to Quake, the co-founders had agreed to keep "Doom 3" in their back pocket in the event they returned to the franchise. (Final Doom, a 64-level follow-up to Doom 2 released in 1996, was neither "final," nor did id consider it a proper numbered sequel, though the game does fit into Doom canon.)

Nintendo had a stipulation of its own: The game could not simply be called "Doom"; that would confuse players, who might think they were buying a port of id's PC game released in 1993. "Doom 64 was never specced as a port," Seeler added. "It was specced as, Midway will come up with an arcade-y version of Doom. Because it was Midway, home of Arcade Legends, plus recent acquisition of Tradewest as the established 16-bit console developer with its track record in 16-bit consoles."

Seeler had most if not all the tools he needed to create a 64-bit Doom at his fingertips. With little effort, he could adapt the code he'd written for Doom on PlayStation. And to his delight, the N64 was up for the challenge. The GPU, or graphics processing unit, had been designed by Silicon Graphics, Inc. (SGI).

SGI's impact on videogame graphics almost turned out very differently. Founded in 1981, SGI distinguished itself as a leader in supercomputing technology that swept through Hollywood. Eyeing the rise of Microsoft Windows and Intel's microprocessor, SGI's executives resolved to push into the videogame market. Their engineers drafted a proposal for a graphics chip and shopped it to Tom Kalinske, then president of Sega of America.

What happened next is up for debate. According to Kalinske, he was excited by the prospect of working with SGI and invited engineers from Sega's headquarters in Japan to fly to America and meet with SGI. Sega's engineers were underwhelmed by shortcomings in the design, and passed on the opportunity, even after SGI worked out the kinks. However, Nintendo's history tells another story, claiming that SGI never considered Sega as appealing a partner as Nintendo, leading SGI to develop a graphics chip for N64 instead.

Although PlayStation ultimately outsold Nintendo 64, SGI's Reality Coprocessor chip—dubbed the RCP—for Nintendo's platform raised the bar for graphical horsepower on a console. Its ability to pump out polygons was such that Nintendo added four controller ports to the console specifically because the N64 was the first home platform able to divide the screen into four discrete displays without significant slowdown.

Aaron Seeler was excited to work with the RCP. "I like all console hardware. Each cycle was too short for me. N64 was really a special time. They had an SGI-designed GPU. I mean those guys had real 3D for years, so it was like being let into a country club after just poking pixels."

Seeler's enthusiasm compelled him to write a rendering engine that tapped into the RCP. For Midway's artists and designers, that meant redesigning Doom's iconic rogue's gallery of demons. Gregor Punchatz, the artist id hired to design characters for Doom and Doom 2, built new models for the Imp, Lost Soul, zombified soldiers, Baron of Hell, Cyberdemon—nearly every monster in Doom lore. Only the Arch-vile, Revenant, Commando, and Spiderdemon were cut from Doom 64's lineup. While the N64 boasted enormous power in some respects, Nintendo's choice of cartridges rather than CD-ROM for storage limited how much data a game could contain.

Even so, Doom 64's characters managed to evoke their PC counterparts while exhibiting personalities all their own. Sprites for monsters, items such as weapons and power-ups, and projectiles such as the Imp's fireball were larger than the originals. They were also derived from polygonal models to accentuate their upgraded appearances. Textures on objects from walls and floors to monsters and weapons were of a higher quality. Techniques seen on the PS1 port of Doom, such as translucent monsters, were applied to create new variants of baddies such as the Imp.

The centerpiece of Doom 64 was its collective batch of 32 levels. In Doom and Doom 2, skies had been made of single, unmoving images, such as the mountainous backdrop of Mars. Doom 64's skies were animated to scroll by at variable speeds. Lightning cracked. Fog settled over terrain, hiding the demons waiting to ambush "Doomguy."

"It was the core of Doom 64's look and feel," said Seeler regarding colored lighting. "It was a trivial thing to implement. The hardware supported vertex coloring at no cost. The work was on the level designers to use it effectively."

A horror-heavy direction, which Midway had stumbled upon while porting Doom to PlayStation, became the focus of Doom 64. Level designers, or LDs, drafted huge spaces that invited exploration but narrowed at just the right places, forcing players to debouch into claustrophobic rooms and corridors where lighting was minimal, and enemies laid in wait.

For Doom on PC, id's designers had crafted triggers to surprise players. Picking up a keycard or walking across an invisible line might open a hidden door and unleash a flood of enemies. Midway's LDs came to Seeler and admitted they felt constricted by those triggers. They were fun, but Doom 64 should do more.

"I proposed a horrible hack where they could sequence and batch up their triggers plus some new triggers for script flow and timing and it was up to them to not do bad things," recalled Seeler. "They really exploited it to inject a bunch of dynamic level behavior."

Walking over a certain section of terrain could trip a trap such as blow darts flying from walls. Other triggers permitted artists to rearrange a map's geometry. On map 02, a giant column pounds into the ground of a courtyard, creating a subterranean environment. To players, those underground passages had not existed moments before. With the flip of a lever or press of a button, maps could take on new dimensions.

Thematically, the combination of atmospheric lighting and Aubrey Hodges' eerie soundtrack encouraged a slower burn. Action punctuated long stretches of exploration and simple puzzle-solving; all the while, Hodges' soundtrack crawled under players' skin. "Aubrey loved Doom like all of us," Seeler remembered. "He sat with the LDs and got a sense of the level and where they were going with it. He would score it, plug it in, and it was just that feedback loop."

Although Seeler did not work alongside John Carmack on Doom 64, he made frequent trips to id to show off prototypes and get the guys' approval. Id's team, buried in Quake and, later, its sequel, managed Midway with as light a touch as possible. Doom 64 had been known internally at Midway as "Project Absolution," and would include a wider variety of textures to spice up levels such as iconography and patterns from Egyptian, Mayan, and Aztec cultures.

Carmack liked how Doom 64 was shaping up, but put his foot down on certain content. "I was sort of the human interface to the N64 performance and capabilities tests," Seeler explained, "as John wanted to make sure technically it hit his requirements of being the highest quality pixels we could get. John was also—correctly—adamant about what the product was not going to turn into despite having easier-to-achieve triangles."

Doom 64 arrived in stores on March 31, 1997. Many critics complimented its audiovisual overhaul, but considered it just another Doom game. For all its graphical techniques and high-poly models, it played similarly to Doom 2: no free aiming, same enemy types and power-ups,

Over time, however, Doom 64 has risen to fan-favorite status. Its slower pace, greater emphasis on exploration and puzzles, and atmosphere that starts out creepy and frequently bordered on terrifying carved out a unique identity for an alternative take on the Doom that id imagined. One could almost view it as a precursor to Doom 3, a horror game with action elements developed and released by id Software in 2004 and supplanted by Doom 2016 and its ilk.

Bethesda Softworks partnered with Nightdive Studios to resurrect Doom 64 for release on March 20, 2020, alongside Doom Eternal. Nightdive designed seven new maps for the re-release and touched up Midway's work to make the game shine on PS4, Xbox One, Nintendo Switch, and contemporary PCs.

That Doom 64 holds up so well even without Nightdive's extra maps and polish is a testament to the vision of Midway's team and the clear passion they had for the project. "I worked with a bunch of talented individuals and we all loved Doom," Seeler said. "That's what it took. We were young and we didn't always get along. I think to this day we all have a copy in our bookshelf and are really proud of how hard it was to thread that needle and come out with a version that will stand for all time and did everybody proud from id and Nintendo to Midway and our customers."

This feature was written based on interviews with John Romero, Aubrey Hodges, Jay Wilbur, and Aaron Seeler. For more details on the making of Doom 64, reader the author's interviews with audio engineer Scott Patterson and composer Aubrey Hodges.

David Craddock

Long Reads Editor

David L. Craddock writes fiction, nonfiction, and grocery lists. He is the author of the Stay Awhile and Listen series, and the Gairden Chronicles series of fantasy novels for young adults. Outside of writing, he enjoys playing Mario, Zelda, and Dark Souls games, and will be happy to discuss at length the myriad reasons why Dark Souls 2 is the best in the series. Follow him online at davidlcraddock.com and @davidlcraddock.