(20 years ago, November 30th, 1998, Looking Glass Studios under publisher Eidos Interactive released Thief: the Dark Project. This hugely influential stealth game came on the heels of one of the most complicated and innovative development periods in the history of the industry. This article tells the story of the project from the developers’ perspectives, using interviews throughout the years to craft a narrative of design focus, studio turmoil, and perseverance which encapsulates all that was great about Looking Glass. Please enjoy!) The games Looking Glass had done up to then, System Shock and Terra Nova and earlier games, used a world divided up into a grid. We all wanted to break free from that. I came up with a strategy using a technology known as “portals” to us to have more flexible world layout and be fully 3D. I put this in a tech demo named “Portal”, probably soon after Terra Nova shipped (but I don’t know for sure). […] It was still an open question how to let designers *build* those worlds with as little pain as possible. I heard that John Carmack was using CSG [constructive solid geometry] to tackle the same problem for the Quake engine, which was being developed around the same time. At first this seemed really problematic to me – there were a lot of things that seemed they’d be hard to do properly, but after some email clarifications from him, I went ahead and gave it a try. I implemented a basic “CSG brush” system and a “compiler” that turned the CSG brushes into a “portal” level. I also created a brush editor, which eventually turned into DromEd. […] Doug Church and I then created a test “level” to validate that the CSG brush idea would be viable — would let designers create interesting and functional levels. Once we saw that it worked, the project rolled forward. –Sean Barrett (2009) I saw an ad for Looking Glass – which is a company I loved, I adored Looking Glass – for a job there as a game designer. I’m like, “I’ll do that!” Surprising to me – I didn’t really have any real qualifications – they ended up flying me up there for an interview and then they ended up hiring me. I was so thrilled. […] About a week after I was there, somebody said “Okay, we want you to spend time working with Doug Church on this new thing,” which at the time was just called “Action-RPG”. They just had these vague titles for things. […] I met Doug and I was a big fan of his work. Sort of like being put in the same room with Spielberg in your first week, with no experience of any kind. He was very generous. He did not treat me like a useless slob, which he probably should have. What did I know? But he was very collaborative and we just started talking about what we wanted to do. –Ken Levine (2011) The Thief team wanted to create a first-person game that provided a totally different gaming experience, yet appealed to the existing first-person action market. –Tom Leonard (1999) One of my responsibilities was to come up with the world and what the aesthetic was. First I came up with something called “School for Wizards”. Then I came up with something called “Dark Elves Must Die”. Then I came up with something called “Better Red than Undead”. –Ken Levine (2011) In terms of fiction and structure. We had a post-Cold War zombies proposal called Better Red than Undead in which you were fighting off zombies in a communist Cold War era and running around and having different groups — communist spies and communist government and Western government and all these different spy groups. Meanwhile, the zombies were trying to take everyone over so you had to pick which groups you were going to ally with and go against while everyone had this common enemy of the zombies. But of course no one gets along so you had to play this delicate game of getting everyone on your side or enough people on your side to get the job done. -Doug Church (Rouse 2005) It was a goofy, 1950’s pulp story. At this point, Doug and I wanted it to be a sword fighting simulator. You were a character who was this CIA agent – it was sort of a campy story – you were fighting communists in Russia, there was also a zombie thing going on there. –Ken Levine (2011) The premise [of Red] was that zombies were basically immune to bullets, so you had to hack them up with swords. –Marc LeBlanc (2013) We had conceived of factions of people in the world being a better foil for the player because you can interact with a group in a slightly more iconic and abstract way than you can interact with an individual. Because someone can come and say, “I speak for these people and we think you’re a bad guy” or whatever. And they can do that in a way that’s a little less personal and direct and therefore has a little less requirement on the AI and conversation engine. It was this idea of having factions who you could ally with or oppose yourself with or do things for or not. -Doug Church (2005) I think there are people who want to join teams and people who don’t and people who are opposed to being on teams. I’ve always been the sort of “I’m not on a team” kind of guy, but I’m fascinated by teams. –Ken Levine (2011) The executive team decided Red was too quirky an idea. They had no idea how to market it and they wanted something where the sword-fighting made more intrinsic sense, rather than a fictional contrivance. –Marc LeBlanc (2013) I definitely wrote a bunch of documents. We were doing mission breakouts and stuff like that, but it was relatively early in the process. They killed it. They didn’t kill “Action-RPG”, they just said “This idea is too far out there”. And they were probably right. –Ken Levine (2011) It became Dark Camelot, which was our reverse Arthurian fiction where King Arthur was a bad guy, and Merlin was this time traveller from the future and you were Mordred the black knight trying to save the setting. And Guinevere was a cool butch dyke. –Doug Church (Gillen 2005) The idea was that the victors wrote the history and actually Arthur was an asshole. You and Morgana were actually sympathetic heroes, and actually you were […] African. Part of the reason they were being treated the way they were was sort of the whole racial thing. –Ken Levine (2011) Your advisor [sic] was Morgan le Fey, who was sort of a good person. Lancelot was this evil jerk and Merlin was a time-traveling marketing guy from the future. All the Knights of the Round Table wore jerseys with logos and numbers, and the Holy Grail was this fake thing that they didn’t think existed but they were using it as a way to continue to oppress the masses and take all their money and treat them poorly. The excuse was that they needed all the money to go find the Holy Grail and they’d just sit around and have parties. So you as the Black Knight had to break into Camelot. -Doug Church (Rouse 2005) The world was more modern than the traditional Arthurian elements. Steampunkish, but with no gunpowder. I remember seeing sketches of Merlin with a top hat, and there was talk of Knights covered in corporate logos like NASCAR drivers… We didn’t want to be straight up orcs and elves; we wanted to build something unique and memorable. Something we could own. –Marc LeBlanc (2013) Ken Levine was writing and designing for it at the time, and I seem to remember that he and Tim Stellmach were referencing more and more 30’s pulp material, which was the root of the pseudo-modernization of the setting. Lot’s of Fafhrd and the Grey Mouser being passed around. –Daniel Thron (2009) As Mordred, you’ll fight to break the yoke of the tyrant king and set your people free. Your quest will lead you through dark crypts and creature-filled catacombs, battling Arthur’s most famous knights and Merlin’s unspeakable creations. –Looking Glass (1996) We wanted to make a story-driven game, but action-orientated — but the more we worked on it, the more the other ideas weren’t quite working out. It was a more organic approach than Underworld and Shock. –Doug Church (Gillen 2005) The missions that we had the best definition on and the best detail on were all the breaking into Camelot, meeting up with someone, getting a clue, stealing something, whatever. As we did more work in that direction, and those continued to be the missions that we could explain best to other people, it just started going that way. -Doug Church (Rouse 2005) The thing that remained throughout almost the entire product is we always wanted to have AIs who when you were walking around a corridor would say, ‘Hey, is somebody there?’ That’s a concept we had almost from the very beginning. All those ideas, the AI would have a state beyond ‘I see you’ or ‘I don’t see you’, ‘I’m attacking you’ or ‘I have no idea you exist’. The actual “It’s going to be a game about a thief” idea came from Paul Neurath. –Ken Levine (2011) Stealth hadn’t been core to our thinking, but we started to bounce other concepts around and stealth came up. And then the obvious thing to us was, “Well, let’s play in the role of a thief.” We want a more singular experience that’s focused on a role. We know what thieves do. Players know what thieves do. It creates an immediate context, which is especially important if you’re doing an innovative game. –Paul Neurath (2018)

We were still struggling with Dark Camelot – he said, “Why don’t we make it a game about a thief?” I think I liked that idea, I don’t know if Doug liked that idea from the outset. I think he grew to like it. […] Doug asked me to start thinking about what that would be like systemically. He and I talked a lot about it. –Ken Levine (2011) Paul had been pushing for a while that the thief side of it was the really interesting part and why not you just do a thief game. And as things got more chaotic and more stuff was going on and we were having more issues with how to market the stuff, we just kept focusing in on the thief part. -Doug Church (Rouse 2005) All that was really retained from [Dark Camelot] was the idea of the player character as [a] less sort of black and white hero and a more kind of Robin Hood figure. –Tim Stellmach (2011) I started thinking about submarine games and stealth fighter games because that was very similar. How powerful you are when you are unseen and how weak you are when you are spotted. […] In a submarine there are layers in the water of different temperatures, very cold water and warm water, and because […] of the density of cold water versus hot water they form pockets, and those are called thermocline layers. Submarines will often go through those and form a barrier sonar. That gives the ocean a geography and terrain. I started thinking about how do we build a terrain that’s based upon sound and visuals. I was originally thinking about sound in particular. –Ken Levine (2011) Sound plays a more central role in Thief than in any other game I can name. Project Director Greg LoPiccolo had a vision of Thief that included a rich aural environment where sound both enriched the environment and was an integral part of gameplay. The team believed in and achieved this vision, and special credit goes to audio designer Eric Brosius. –Tom Leonard (1999) I think one of the ways Looking Glass was fairly forward thinking was that they brought people in-house – so you can live with the game and absorb the game – and then took the step to put a lot of the integration abilities into non-coder’s hands. I didn’t know how to code. In Terra Nova I remember taking stuff, have to walk over to the programmer I was working with, “Okay, now do this. Oh, don’t play that.” It had no control over volume or panning or anything. […] In Thief we developed a whole text file-based editing system. –Eric Brosius (2011) One of the development goals for the Dark Engine, on which Thief is built, was to create a set of tools that enabled programmers, artists, and designers to work more effectively and independently. The focus of this effort was to make the game highly data-driven and give non-programmers a high degree of control over the integration of their work. Primarily designed by programmer Marc “Mahk” LeBlanc, the Object System was a general database for managing the individual objects in a simulation. It provided a generic notion of properties that an object might possess, and relations that might exist between two objects. –Tom Leonard (1999) Anytime something happened in the game, it would spit out an event to the audio engine. Then we could basically make up any names for tags. We could tag any item with something like this. Once they did that, I could go in and add in all the footstep sounds myself. […] Every time something was drawn they would send a Create event to the sound system and I could choose whether I wanted to hook something up to it. There was just this giant database [to] look up an event and a series of tags, if something matched it would play a sound. […] I also did a lot of stuff like making test levels. I would build myself a room that was 20 foot by 20 foot with all the textures that the game has, with all the styles. Here’s the gravel, and here’s the sand, and here’s the grass, and here’s the rock, and here’s the marble. I could bring crates in there and after we hook up sounds to the physics, I’d throw them around and test them. This was like a virtual foley studio. –Eric Brosius (2011) I was so taken by the digital audio from System Shock 1. As crude as the graphics were, the audio was so evolved already once you had digital audio. It’s just recording stuff. You had guys like Eric Brosius and Kemal [Amarasingham] and Greg LoPiccolo who were so good at doing audio and ambient beds that Looking Glass audio was so far ahead of everything else. […] It was such a powerful tool, we really wanted to exploit that. –Ken Levine (2011) When constructing a Thief mission, designers built a secondary “room database” that reflected the connectivity of spaces at a higher level than raw geometry. Although this was also used for script triggers and AI optimizations, the primary role of the room database was to provide a representation of the world simple enough to allow realistic real-time propagation of sounds through the spaces. –Tom Leonard (1999) The fact that our sound propagation in Thief was so good [is] because we did not want to deceive you about where things that you were hearing were. There was a lot of work put in to making the sound propagation quite naturalistic. So sound would propagate properly through doorways and not through solid walls and stuff. Because of that, we had all this data and we could attenuate sound when there was a closed door so that wouldn’t fool you. –Tim Stellmach (2011)

I remember when they first got the physics of the guard walking around, Greg LoPiccolo – the project manager – was showing it off at a 4:00 Friday team meeting. He showed this guard walking around and there was a bug in it, so this guard’s legs went out of control. Remember the Monty Python sketch? -Steve Pearsall (2017) We had the first project-induced suicide this week. It was one of our AI’s. He’d just got his shiny new physics model on his sword, and provoked by the appearance of the player-character, wound up and swung with mighty abandon. Following through less than adroitly, he managed to hit himself and promptly keeled over. –1998-01-23 Looking Glass Project Diary We put an Easter Egg in Thief: Gold. It was actually my idea because of my video background. I suggested it and other people took it and ran with it. “Let’s do an outtakes reel! Let’s take the funniest bugs we had and put them in a special level.” -Steve Pearsall (2017) There’s a lot of difference between the levels in Thief. Not only because the designers had such different approaches […] but the testers were also different. Each tester was dedicated to a designer and to a level. The tuning is rather different and the expected play path is different as well. –Lulu Lamer (2018) The level designers on Thief 1 worked with our spaces and tried to get a feeling for what worked well and what didn’t when we watched other people playtest or our QA staff would report things to us. –Randy Smith (2018) Whoever had Randy’s Cathedral level spent so much time trying to get outside of the walls and point out every little area where you could wiggle to get your physics model outside the fence. […] Eventually Randy and Mahk were like, “Screw it. If you want to get out of the world, if you want to be a jerk and do that, go to town.” –Lulu Lamer (2018)

Comment in a Reddit AMA thread, 2018. https://www.reddit.com/r/gaming/comments/9rbn0x/we_are_paul_neurath_warren_spector_and_the_dev/ Thron, Daniel. Interview with Through the Looking Glass, 2009. https://web.archive.org/web/20181126045036/https://medium.com/@Dominuz/out-of-the-shadows-daniel-thron-86487d9e30e5 Verelli, Sara. Interview with Matthew Weise, 2011. http://gambit.mit.edu/updates/2011/05/looking_glass_studios_intervie_2.php Wells, Nate. Interview with Irrational Games, 2010. https://www.youtube.com/watch?v=AYdIVAfLNnA Yaus, Jeff. Interview in Next Generation, March 1997. https://archive.org/details/NextGeneration27Mar1997/page/n55 Looking Glass Project Diary preserved from the Looking Glass website found here. The earliest archived version can be found here.