Abstract
This monograph examines the game pitch document written by Condor, Inc. for Diablo, released in 1996 by Blizzard Entertainment, and places the game in the context of developments of Procedural Content Generation, marketing of Loot Boxes, and the impact of the collectible card game Magic: The Gathering on its development.
Introduction
Diablo (1996) is one of the first examples of the genre of action role playing games with roguelike elements. The term “roguelike” derives from the 1980 video game Rogue which was notable for its procedurally-generated levels and turn-based combat. Levels took the form of inter-connected rooms populated with traps and monsters, presented from a top-down perspective with simplistic ASCII graphics. Its basic gameplay elements eventually formed the basis of an entire genre, encompassing such games as Moria (1983), NetHack (1987), and Mystery Dungeon (1993), as well as more recent titles like Tales of Maj’Eyal (2012). Diablo revolves about a group of fantasy warriors hunting the demon lord Diablo, who is threatening the village of Tristam. Players follow a series of quests that take them through several increasingly difficult dungeon levels, and eventually into Hell itself. The player coming from one of three classes: the Warrior, the Rogue, and the Sorcerer. Each class has their own abilities set. Characters gain experience based on killing monsters and collects loot from defeated enemies and from the level itself. The game would go on to spawn an expansion pack, and two numbered sequels with expansions.
The following is an analysis of the original pitch document by Condor, Inc. Condor (1994) for the game Diablo published by Blizzard Entertainment. The document was made available at GDC 2016 by David Brevik, a co-founder of Condor (which later became Blizzard North) providing a first look at an industrial trade secret up to this disclosure. In examining this document we provide a historical look at the game of Diablo, place its contributions to the creation of a new genre of gaming in context with current games design and development techniques, and examine the design methodology. Further, we examine the planned marketing of content for Diablo, its expansion packs and sequels, and look at how plans made now over twenty years for the games release marketing could be implemented with the current technological framework of digital distribution and procedural content generation.
Procedural content generation
Procedural Content Generation (PCG) is the development of game assets, such as levels, items, and enemies, via an algorithmic process rather than by a human developer. Online PCG are method which produce games content during the runtime of the game. For example, a level is generated via an algorithm in a loading screen as the player reaches it. Parberry defines PCG as “the automatic creation of video game content, where content means anything that is traditionally created by an artist or a designer, such as maps, textures, levels, and objects. Content creation usually requires equal parts creativity and scutwork. The aim of procedural content generation is to relieve the designer of the scutwork in ways that create more opportunities for creativity” Parberry (2018). Togelius et al.’s definition Togelius et al. (2011) is that “Procedural content generation (PCG) in games refers to the creation of game content automatically using algorithms” and takes a rather broad definition as to the term content and techniques which would fall under the term of an automatic algorithm.
The synthesis found in these definitions are the ideas of the generation as a process of creation on the part of an algorithmic framework rather than on the part of a designer. However, the designer is still involved in the development of the generation to still meet with the overall thematics of the game; the issue is to what extent the designer is involved and to the algorithmic design. In this case Diablo is designed with the use of random level generators in mind, see Fig. 1, and presents an early example of these techniques being used in a game with mass market appeal by a large publisher, i.e. AAA games.
Diablo’s pitch document highlights the use of PCG as a prominent feature of the game: The heart of Diablo is the randomly created dungeon. A new dungeon level is generated each time a level is entered, using our Dynamic Random Level Generator (DRLG) System. Rooms, corridors, traps, treasures, monsters and stairways will be randomly placed, providing a new gaming experience every time Diablo is played. In addition to the random halls and rooms, larger ‘set piece’ areas, like a maze or a crypt complex, will be pre-designed and will appear intact in the levels. This system facilitates the inclusion of puzzles and traps, and helps the addition of thematic elements. Deeper levels will contain progressively more difficult creatures and hazards. A character’s quest must end with the defeat of Diablo, located deep in the dungeon. Condor (1994)
Level structure plan from the Diablo Pitch Condor (1994). The town on top followed by level after level of the procedurally generated dungeon.
The major influences for Diablo was the card game of Magic: The Gathering, created by Richard Garfield, that allows players to build their own decks, this has elements of combinatorial exploration which would later be seen in the DRLG method. An examination of the game Weisman (2007) “[d]eck construction was the key to Magic’s success [as a product]” and the “mathematical genius of Magic is diversity of variable deck construction tactics, which revolutionizes how people learn, play, and enjoy games.” Baur comments on the “[rarity] that a truly original rule shows up, such as the deck construction rules that made Magic: the Gathering …a breakout hit” Baur (2012). The amount of content required to maintain a good control over look and feel is large. This comes from the combinatorial explosion that occurs with the addition of size such as room tiles, creating an exponential increase in the potential levels. However, this same explosion is not seen in the number of combinations of a room set which is polynomial to the number of available title elements keeping size constant. This perhaps explains some of the comments made by Wilson talking about the amount of required content for a size 12 to 15 room dungeon to seem random requiring selection from a set of 80 element rooms from which to draw the selections Lopez (2008). Such a combinatorial explosion of content also was a major setback to Magic as highlighted by the production of the original release requiring “over 300 pieces of color art
Procedural content generation for Diablo like levels has been examined in Valtchanov and Brown Valtchanov and Brown (2012), which examines the use of Genetic Algorithms as a method to provide a more controlled experience than the DRLG. It pays attention to the inserting of special rooms, much like the pitch document’s ‘set pieces’, though it was published without the knowledge of a pitch document. The use of recurring and set pieces has been applied in other generative methods in games since the release of Diablo. Ashlock and McGuinness Ashlock and McGuinness (2014) highlight their work as being expressly examined for the use of PCG in D&D like games.
Diablo’s sequels however, did much more to implement the pitch. Whereas, the tiles shaped spaces in Diablo were single cells or one isomorphic square, later editions changed this development pattern for the dungeons into larger artistic tile spaces. It was similar to a joining of a number of set pieces rather than making it up from random placements.
Diablo is widely considered one of the first games in the Action RPG genre. Actions RPGs involve a real time applications of spells and attacks as opposed to a number of RPG games which have a number of actions in a turn based system, or have modifications allowing for interrupting of actions in an event based queue. However, this innovation would not be present until the development progressed. The pitch document describes the game as being close to the tabletop based RPGs, such as D&D, or other isomorphic video games.
There is a mention of a time based element on the actions of players. This forces a movement and urgency to the actions of players. As this time allowed mechanism was reduced over the development and the Action RPG was created. For an online game this mechanism was also placed as an anti-away from keyboard (AFK) mechanism to ensure the flow of the game. This element also allowed for the inclusion of RPG elements such as action points or initiative.
Story and narrative
The “face” on Mars demonstrates a case of Pareidolia. Photo by NASA/JPL Voyager mission photo #035A72.
The pitch shows that the details of player character’s back story is not a high priority in the game. The character is completely flat, having no notable characteristics other than the fact that their family had been killed by Diablo. This is a very generic description for what is to be the protagonist. By leaving the protagonist character blank this could encourage the imprinting of a player’s own ideas on the character and encourage the experience of role playing. In Understanding Comics McLeod (1993) the idea of the detail in animation is used in a similar manner. As Scott McCloud writes, character designs with low detail encourage the reader to “fill in the blanks” with their own subjective impressions, which then leads them to identify with the characters more strongly. Low detail allows for a player to become more attached into the world and play as the character as “simplifying characters and images towards a purpose can be an effective tool for storytelling in any medium” McLeod (1993). Human beings have remarkable processes for discovering faces and placing themselves in their place. Pareidolia refers to the phenomenon where the human brain detects a pattern, usually a face, where none exists. The man in the moon, the face on mars (see Fig. 2), and the happy look of automotive front facias all exhibit this effect. Such images trigger a response in the ventral fusiform cortex, also known as the fusiform face areaRieth et al. (2011), and have been used in such art forms as photographic mosaics Brown et al. (2011). McCloud uses this phenomenon as part of the argument to see ourselves in more limited expressions. Displaying images of north American style power outlet, car fronts, a Kraft Parmesan cheese top, and a simple emoticon smiley face he explains that “[w]e humans are a self centered race. We see ourselves in everything. We assign identities and emotions where none exist and we make the world over in our image” McLeod (1993). Thus, by leaving the background of the main character rather vague it gives us such a purposeful simplification as a tool for storytelling, the background motivations of the player character are ill defined and thus the player is free to roleplay them. Games such as Fallout 3 have utilized the character creation process as part of the storyline, everything from defining the player look, their skillsets, and their perks is told via the medium of a flashback at the start of the game. The player progressing from all the way from birth, to being a toddler, to their birthday party acting as a milestone in their maturation of (wo)manhood within the vault society, and finally to standardized testing for job placement in the vault. All of these elements define the character, but are only vignettes of the journey the player has had until they leave the vault and the adventure begins properly. Fallout: New Vegas extended this to the point of being amnesiac and not having any backgrounding beyond knowing someone had shot you in the head giving the motivation for revenge. Fallout 4, gave a more well defined background on the characters, to the point of having a spouse and child which becomes part of the main story of the game. Fallout 4, by virtue of giving such a detailed background, locked off a number of the possibilities of the player defining a character.
The roguelike nature of the game can be seen in also enforcing a permanent death of the player as it states “the character will be erased completely from the hard-drive and the player must start from scratch” Condor (1994). Such a penalty for death is seen in a number of games, and the Hardcore mode of Diablo and its sequels explored this, in normal practice this would not be applied and instead there would be a reduction in gold and in the quality of the worn items at the time of the player’s death. The destruction of the player character completely from the hard drive has a heavy permanence.
The pitch document details an extensive marketing plan, one full page is devoted to the examination, that goes beyond the initial release of just the game. The marketing plan highlights the expandable nature of the product due to such features as the DRLG. The pitch compares this to the collectible card game of Magic: The Gathering they explore the possibility of small expansion packs on disks for sale at stores for a small additional cost. Magic: The Gathering was “Mathematics professor Richard Garifield[’s] …pet project – an expandable card game
Blizzard’s recent multiplayer shooter Overwatch (2016), for example, allows players to purchase or earn “loot boxes” that contain a random assortment of cosmetic items – character skins, spoken dialogue, victory poses, etc. As with Magic cards, these items vary in rarity, meaning that players will often have to purchase numerous boxes in order to acquire the desired item. Similar systems have also become popular in free to play games, which do not charge an upfront fee, but profit entirely from selling in-game items. Similar items can be seen in League of Legends (2009), the Call of Duty series, and Sports games such as FIFA, have also moved to such a marking model – with mixed results. The model has become an integral part of game marketing and monetization Jaakko and Olli (2009). In developments like Steam, such marketing not just games, but the distribution model. This movement from just a product driven market to the development of platforms has been seen in a number of businesses including those produced by Microsoft and Google, and this model creates new streams of revenues by linking together previously separate or third party developments. Microsoft for example opened the Minecraft platform up to Modders and made some hires from the modding community to improve their systems Zhu and Furr (2016).
Booster pack of Magic: The Gathering.
The marketing strategy suggested in the pitch document shows that a monetization system very similar to the presently dominant one had been conceptualized long before it ever became technologically feasible, and seems to have taken considerable inspiration from Magic: The Gathering. While it is unclear why the system was not adopted in the final version of Diablo, we speculate that the need to distribute these booster packs on physical discs, rather than digital transmission over the Internet, proved too costly. An old style expansion pack, which bundles all of the new content on a single disc and sells it at a high price, is simply a more cost-efficient distribution system in the absence of widespread Internet use.
Replayability and rejuvenation of the game over time is highlighted as a major selling feature of the game. Techniques of automatically balancing procedural content however, are in early stages and such limitations were mostly based on player and enemy leveling, ensuring that a player is matched with an appropriate level of challenge based on their skill levels. This learning curve defines the process of learning on the part of the player and the expected difficulty of levels. If the perceived difficulty of the level is bellow the learning level, the player will become bored with the content, too high and thy will be frustrated. The designer works to ensure that the challenge to the player meets with their learning level, or at least is not extremely far away leading to disengagement and then to the player leaving the game for another.
Diablo’s pitch document portrays a game not too far removed from the current set of Action RPGs. PCG in terms of the level designs would be introduced into the Action RPG by the Dynamic Random Level Generator, and it would go on to influence a number of later designs and the creation of new generators. The time based turn model after the development process would move Diablo away from becoming another tabletop role playing game, except implemented digitally, into a action based game with RPG elements. RPG elements would begin to move into more general action adventure games and then into first person shooters. These elements would include character creation, changing of skills and weapons, and gaining loot. The marketing section would fit well with the current methods of digital distribution, free to play games, and the quantization of games on the level of individual assets. This business model would be demonstrated first in collectible trading card games, such as Magic: The Gathering which is noted as a clear inspiration for the developments in Diablo. However, the technology which would ease the distribution was not available. Current frameworks for digital distribution have removed the barriers to entry, and consumers are to a level of acceptance of the idea of digital items as having real world monetary value. While not implemented in Diablo originally, the pitch document provides a clear example of the planning for such inclusions in future designs and games.