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Educational Feature: A History and Analysis of Level Design in 3D Computer Games - Pt. 1
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Educational Feature: A History and Analysis of Level Design in 3D Computer Games - Pt. 1

April 25, 2006 Article Start Previous Page 3 of 3

The Doom engine supported a number of new features that finally made realistic and interactive environments possible. Instead of merely featuring doors that could be opened, Doom featured the ability to alter the game world by using in-game switches and “triggers” to activate events. These events could range from a set of stairs rising out of the ground to unsealing a room full of ravenous near-invisible monsters to bridges emerging out of toxic slime. Additionally, Doom added in lifts, which could raise players to different levels inside the game world or, if used slightly differently, could act as pistons and crush players against a ceiling. Further, the Doom engine’s support of variable height floors and ceilings also meant that in addition to being able to move on all three axes, more complex architecture could also be created. Tables, altars, platforms, low hallways, ascending and descending stairs, spacious caverns and other objects could all be created using geometry.

The ability to trigger events that could release monsters or alter geometry led level designers to create a number of surprisingly complex traps for players to uncover as they played through the game, from rapidly rising floors to bridges that would sink into toxic sludge if players moved too slowly. A frequent occurrence in Doom would be players being penalized somewhat for grabbing caches of equipment and ammunition; frequently, if a number of valuable items were left in plain view and easy access, approaching them would unleash an attack. This gameplay mechanic was present in both the 1994 release of Doom II and the 2004 release of Doom 3, though some players in 2004 were notably less amused. However, for Doom players, this was interactivity and detail that they had never seen before.

Doom’s support of variable height ceilings and floors meant that players were now free to move up and down in the game world, but not without limitations. Due to the implementations of the engine technology, the game could not support rooms over rooms, which meant that level designers could not have a second floor directly over the first floor, as is common in architecture. Nevertheless, this was not a significant limitation, and the ability to move around on all three axes was a major technical achievement. With careful attention to detail, level designers could deceive players into thinking the architecture was more complex.

The increasing architectural complexity was not limited merely to height changes, as the Doom engine also supported walls that were at angles other than 90 degrees (Kushner, 135). This was one of the most visible changes from the architecture present in Wolfenstein, allowing much more realistic shapes. The engine supported only horizontally sloped surfaces, however, and did not support vertically sloped surfaces. This meant that walls could have an angle to them, but that ramps and other vertically sloped surfaces were not possible. As a consequence, all floors and ceilings in Doom were completely flat.

John Carmack also used the Doom engine to greatly expand upon the previous implementations of texture mapping, now allowing textures to the ceilings and the floors, making for an improved appearance. Doom also supported a texture that could be projected onto the “sky”. This meant that when players looked outside or, as was often the case, traveled outside, they could see an image of the sky and the surrounding terrain. These textures could be changed, depending on what episode of the game, or level, the player was in. The appearance of the sky textures was a subtle confirmation that until now the majority of 3D First-Person Shooters had been confined to narrow internal corridors, with no acknowledgement of an outside world.

In addition to architectural advances, Doom also added the ability to alter the light levels in a level. All levels in Wolfenstein 3D and earlier titles were lit at the same level throughout, with no variations. This led to a very artificial appearance, since areas hundreds of virtual feet away were lit identically to areas just a few feet from the player. In Doom, however, level designers could alter the lighting of certain areas, or even add simulated dynamic lighting, such as flickering lights. In many cases, the ability to alter the lighting level was used to plunge the player into darkness at highly inopportune moments, leading to players panicking as they were attacked by nearly unseen opponents, desperately searching for a switch or trigger that would reactivate the lights. This use of actual sources of light would be expanded upon further as game engines advanced.

The level designs for Doom were accomplished using much more advanced tools than previous id titles. Romero wrote an engine-specific level editing program called DoomEd, which ran on the NeXTSTEP operating system, which was light-years more advanced than DOS, the then-current standard PC operating system or the newly developed Microsoft Windows (Romero). Developed by NeXT Computers, a company founded by ousted Apple Computer co-founder Steve Jobs, the NeXTSTEP operating system and NeXT hardware was a powerful development tool for software designers, and provided a perfect medium for John Carmack to develop the next-generation engine that would power Doom. That meant, however, that all development had to be done on NeXT systems, and then ported over to the PC. This, combined with the new complexity of designing worlds in a three-dimensional editor meant that the days of a simple tile-based editor to create levels were over.

Despite the increasedrealism that Doom allowed, from a design perspective the levels were still more suggestive of a locale than representative. The levels could be detailed in a way that gave the impression of a military base or demonic setting, but the limitations of the engines prevented more detailed representations of the environments. Doom did represent a major step forward in level design complexity and innovation, but it proved to be an even better illustration of the potential of the First-Person Shooter to actually simulate real-life locations. Doom also illustrates that levels do not have to be based on easily recognizable locations in order for players to enjoy them, nor do they have to conform to preconceptions of what an environment should look like. Few would argue that the levels in Doom accurately represent what a research facility on an alien world would look like; indeed, the fact that the world is simultaneously familiar and abstract (Kushner, 136) may be a fundamental part of the charm of the game. The emphasis in Doom was not in levels that were recognizable, but in levels that were fun to play.


Doom defined the first person genre, but more importantly
it made the idea of users modifying a commercial title
acceptable to developers.


The emphasis on playability, the ephemeral “fun factor” is an important aspect of level design. Early Doom levels focused heavily on replicating the appearance of an actual military facility (Kushner, 136), but the fact is that most real-life locations are poorly suited to serve as game environments A variety of factors conspire against the level designer that seeks to use actual buildings and spaces in a simulation, but the primary issue is that most real world locations are not designed to be played in, making for an unmemorable experience. The key goal of a good level design is to balance setting with flow, the balance between exploration and moving through a plausible game world and interacting with the inhabitants and items in that world. Early Doom levels were likely accurate in terms of architectural style and function (Kushner, 136), but were lacking in two distinct areas. First, the levels failed to highlight the innovations of such a groundbreaking engine. Second, the levels failed to provide compelling or innovative gameplay to the player, a cardinal sin in level design. Recognizing the problem, later level designs emphasized the fast paced “run and gun” nature of the game, and also served to showcase the technical advantages of the engine.

A later iteration of the Doom series, id software’s 2004 release of Doom 3, took a much different approach to level design, laying out highly detailed environments that looked very much like what one would expect a base on Mars to resemble. However, designers chose to take a progressive approach, wherein early levels appeared hyper-real, but as players proceeded further into the facility, the levels grew increasingly abstract, laced with pseudo-organic structures and, eventually, bringing the player into a gothic nightmare vision of Hell itself.  With an additional 11 years of technology, perhaps level designers were now better able to bring the original vision of Doom to life. Conversely, the progression into more complex and inventive levels later in Doom 3 may be an example of level designers becoming more comfortable with their tools and the game engine as development continues. Such a trend is certainly not limited to Doom 3, and is surprisingly common in game development. In several cases, levels designed early in a project are later revisited and improved upon by level designers that are now much more comfortable with their tools. In some certain cases, such as 1998 release of Valve Software’s Half-Life, the development team may completely scrap earlier level designs and start anew, though financial constraints usually prevent such drastic steps.

Despite the many technological advances that Doom displayed, there were still some sacrifices made in the name of speed. Just as with Wolfenstein 3D, enemies and many objects in Doom were not constructed of polygons, and thus not actual 3D objects. Instead, the game rendered enemies, items and many decorative objects as sprites, simple two-dimensional graphics. The advantages of sprites are that they require little processing power to generate, and sprite-based characters could be designed relatively quickly. For Wolfenstein, characters were manually drawn by artists, but for Doom several characters were created as clay models, and then digitally photographed in various poses. These digital images were then adjusted and used as the various character attack and movement animations (Kushner, 134-135). This approach reduced overhead while improving the quality of the animations. One of the major downsides to using sprites, however, is that they are two dimensional, meaning that they don’t actually look like part of the game world, but instead like moving paper cut-outs. While this could be compensated for to some degree, it meant that dead enemies and objects lying on the ground would always appear to be facing the player, even if the player did a full circle around the objects. Essentially, the objects appeared to have only one side, and the player could never see the sides or back of these objects. While annoying, the fast pace of Doom meant that this was not a priority issue, and would eventually be dealt with when engines became fully three-dimensional.

Before Doom, level design had centered on a single player experience. That is, levels were laid out only with one person in mind, the player, and how the player would progress through the level. Doom, however, added the now-common idea of multiplayer gaming into the mix, which it called DeathMatch. Designing levels for multiplayer requires a different set of priorities for level designers, depending on if the map being designed is for co-operative play or, more commonly, a map for players to do battle against one another, deathmatch-style. Level designers need to be aware of the size of the map and how many players they are designing the map for.   Too big a map and players may never find one another, but too small a map and all semblances of tactics and strategy is lost as whoever grabs the biggest weapon first will likely dominate. In modern titles, multiplayer maps are usually specifically designed for multiplayer play, though sometimes they are modifications or tweaks of levels found in the singleplayer game. More often the levels multiplayer levels are custom-designed for multiplayer play. In Doom, the single player levels did double-duty as multiplayer levels for deathmatch, as well as for the co-operative play. When designing for multiplayer, flow through the map is very important, as players should be able to quickly move from one place to another, particularly if being pursued.  Weapon and item placement are also extremely important in multiplayer games, as placing items such as armor or health replenishment too close to powerful weapons can again unbalance the game, particularly if a player decides to “camp” around these items and prevent other players from obtaining them. Several of the singleplayer Doom maps were extremely popular deathmatch levels, a testament to their excellent design. Doom also had another advantage over more modern titles.  Each of its maps was a stand alone map, not structurally linked to the map before or after it, allowing for a unified theme between maps but not requiring maps to directly flow into one another. More recent games such as Ritual’s SiN, Valve’s Half-Life and Half-Life 2 and id’s own Doom 3 features a unified level structure, where each level is a single portion of a contiguous whole. Such level architecture helps to create a feeling of being part of a larger world in the single player game but means that these levels, typically, are unsuitable for Deathmatch.

The emphasis on single player storytelling and plot structure has also led to a steep decline in the number of titles that allow cooperative play, since many of the techniques and missions that are appropriate in single player are unworkable in multiplayer. Further, since the emphasis in a single player is the individual player, there is often some form of puzzle solving in order to allow the player to proceed. In Doom, this typically consisted of finding a key or switch to open a locked door, but in newer games the puzzles or obstacles have increased in complexity. Puzzles are usually structured such that they work only if there is one person attempting to solve them, and the addition of anywhere from one to three additional players either renders the puzzles too simple or possibly breaks the game. As such, commercial designers typically do not create maps suitable for cooperative play as it is simply not time or cost effective.

Fortunately, Doom was also a leader in user-modifiable content. The game was essentially in two separate parts, with the engine being one part and content such as levels, sound effects, animations and music being contained in special files called WADs, or .wad files. By separating the content from the engine, it meant that individual users could modify the program by themselves, adding in new content (Kushner, 166). Players modifying games was not a new concept, since players had been developing content for text-based role playing games for years, not to mention hacking Wolfenstein 3D and other titles to change the content. Hacking the executable files, the program itself, was a concept that wasn’t embraced by the developers, since there was nothing to prevent people from distributing the hacked executable, and thus the game. That meant software piracy, which meant lost profits (Kushner, 166-167). By making the game easily modifiable, Carmack and id software hoped to prevent piracy while encouraging creativity.

The decision to make Doom easily modifiable led to an explosion of creativity. Users began creating their own level editing programs and their own levels, along with new music, new characters and entirely new textures. Drastic modifications, called Total Conversions, such as Aliens Total Conversion emerged, transforming the corridors of Doom into the Atmosphere processor or Med Labs from the James Cameron film Aliens, complete with facehuggers, Aliens and pulse rifles. Level editors such as Brendon Wyber’s Doom Editor Utility or DEU gave players a graphical interface allowing them to modify existing Doom levels or create them from scratch, while Greg Lewis’ DeHackEd, went far beyond the .wads and allowed alteration of the executable itself (Kushner, 168). This gave incredible power to the emerging modification, or mod, community, and this power was the key to enabling the total conversions. The mod community would come to be an important component of game development in the coming years, serving as a recruitment pool for the growing ranks of game developers.

Check back with Gamasutra Friday, April 28, 2006 for the second half of this feature!

[About the author: Sam Shahrani is an M.A. candidate at Indiana University in the Master’s in Immersive Mediated Environments program through the Department of Telecommunications. He can be reached via e-mail at [email protected]]



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