Colossal Cave Adventure
Colossal Cave Adventure is a text-based adventure game, released in 1976 by developer Will Crowther for the PDP-10 mainframe computer. It was expanded upon in 1977 by Don Woods. In the game, the player explores a cave system rumored to be filled with treasure and gold. The game is composed of dozens of locations, and the player moves between these locations and interacts with objects in them by typing one- or two-word commands which are interpreted by the game's natural language input system. The program acts as a narrator, describing the player's location and the results of the player's attempted actions. It is the first well-known example of interactive fiction, as well as the first well-known adventure game, for which it was also the namesake.
The original game, written in 1975 and 1976, was based on Crowther's maps and experiences caving in Mammoth Cave in Kentucky, the longest cave system in the world; further, it was intended, in part, to be accessible to non-technical players, such as his two daughters. Woods's version expanded the game in size and increased the number of fantasy elements present in it, such as a dragon and magic spells. Both versions, typically played over teleprinters connected to mainframe computers, were spread around the nascent ARPANET, the precursor to the Internet, which Crowther was involved in developing.
Colossal Cave Adventure was one of the first teletype games and was massively popular in the computer community of the late 1970s, with numerous ports and modified versions being created based on Woods's source code. It directly inspired the creation of numerous games, including Zork, Adventureland, Mystery House, Rogue, and Adventure, which went on to be the foundations of the interactive fiction, adventure, roguelike, and action-adventure genres. It also influenced the creation of the MUD and computer role-playing game genres. It has been noted as one of the most influential video games, and in 2019 was inducted into the World Video Game Hall of Fame by The Strong and the International Center for the History of Electronic Games.
Gameplay
Colossal Cave Adventure is a text-based adventure game wherein the player explores a mysterious cave that is rumored to be filled with treasure and gold. The player must explore the cave system and solve puzzles by using items that they find to obtain the treasures and leave the cave. The player types in one- or two-word commands to move their character through the cave system, interact with objects in the cave, pick up items to put into their inventory, and perform other actions. The allowable commands are contextual to the location, or room, the player is in; for example, "get lamp" only has an effect if there is a lamp present. There are dozens of rooms, each of which has a name such as "Debris Room" and a description, and may contain objects or obstacles. The program acts as a narrator, describing to the player their location in the cave and the results of certain actions. If it does not understand the player's commands, it asks for the player to retype their actions. The program's replies are typically in a humorous, conversational tone, much as a Dungeon Master would use in leading players in a tabletop role-playing game.The original 1976 version of the game contains five treasures which can be collected. Although it is based on a real cave system, it contains a few fantasy elements such as a crystal bridge, magic words, and axe-wielding dwarves. The player can die by falling into a pit or being killed by the dwarves, but otherwise the game has no ending or goal beyond finding the treasures. The 1977 version of the game, upon which later versions were based, adds ten more treasures and more fantasy elements. It also adds a points system, whereby completing certain goals earns a predetermined number of points. The ultimate goal is to earn the maximum number of points—350, in the 1977 version—which involves finding all the treasures in the game and safely leaving the cave.
Development
Crowther's original version
Colossal Cave Adventure was originally created by William Crowther in 1975 and 1976. Crowther and his ex-wife Patricia were both programmers and cavers and had extensively explored Mammoth Cave in Kentucky, the longest cave system in the world, in the early 1970s as part of the Cave Research Foundation. In 1972, Patricia led the expedition that found a connection between Mammoth Cave and the larger Flint Ridge Cave System. In addition to caving, the pair produced vector map surveys of the cave: they transcribed the survey data of the cave from "muddy little books" into a teleprinter terminal in their house, which could send and print messages from programs running on the central computer and was connected to a PDP-1 mainframe computer at Bolt, Beranek and Newman where William Crowther worked. This data was then fed into a program developed by the pair that generated plotting commands onto punched tape, which were then fed into a Honeywell 316 minicomputer attached to a Calcomp drum plotter at BBN to print paper maps. These maps were some of the earliest computer-drawn maps of caves.In 1975, after he and Patricia divorced, William Crowther stopped caving with the Cave Research Foundation. Driven by what he later described as an increase in spare time combined with missing his two daughters, he began working on a text-based game in Fortran on BBN's PDP-10 mainframe, interfacing through a teletype printer, that they could play. He combined his memories and maps of the Mammoth Cave system, particularly a 1975 map of the Bedquilt area of the caves, including Colossal Cavern, with elements of the Dungeons & Dragons campaigns that he played with friends to design a game around exploring a cave for treasure. Crowther wanted the game to be accessible and not intimidating to non-technical players such as his children, and so developed a natural language input system to control the game so that it would be "a thing that gave you the illusion anyway that you'd typed in English commands and it did what you said". Crowther later commented that this approach allowed the game to appeal to both non-programmers and programmers alike, as in the latter case, it gave programmers a challenge of how to make "an obstinate system" perform in a manner they wanted it to. This approach was also developed to allow the game to be played on a teletype printer, rather than rely on user interface elements used in programs designed for monitors.
The initial version of the game was about 700 lines of code, plus another 700 lines of data such as descriptions for 66 rooms, navigational messages, 193 vocabulary words, and miscellaneous messages. Once the game was complete, in early 1976, Crowther showed it off to his co-workers at BBN for feedback, and then considered his work on the game finished, leaving the compiled game on the mainframe before taking a month off for vacation. According to one of Crowther's then-coworkers in 2007, "once it was working, Will wasn't very interested in perfecting or expanding it." Crowther's work at BBN was in developing ARPANET, one of the first networks of computers and a precursor to the Internet, and the PDP-10 mainframe was part of that network. During his vacation, others found the game and it was distributed widely across the network to computers at other companies and universities, which surprised Crowther on his return. The game did not have an explicit title in it, simply stating "WELCOME TO ADVENTURE!!" as a part of the opening message and having a file name of ADVENT; it was referred to as both Adventure and Colossal Cave Adventure, with the latter becoming the more common name over time. Most computer terminals at the time did not have monitors, and players would instead play the game over teleprinters connected to the mainframe.
Woods's modifications
One person who discovered the game was Don Woods, a graduate student at Stanford University. Woods found the game on a PDP-10 at the Stanford Medical School and wanted to expand upon the game. He contacted Crowther to gain access to the source code by emailing "crowther" at every domain that existed on the ARPANET. Woods built upon Crowther's code, introducing more high fantasy-related elements such as a dragon. He changed the puzzles, adding new elements and complexities, and added new puzzles and features such as a pirate that roams the map and steals treasure from the player or objects that could exist in multiple states. He also introduced a scoring system within the game and added ten more treasures to collect in addition to the five in Crowther's original version.According to cavers who have played the game, much of Crowther's original version matches the Bedquilt section of Mammoth Cave with some passages removed for gameplay purposes, though Woods's additions do not as he had never been there. According to William Mann, a caving compatriot of Crowther who played both versions when they were developed, Crowther was focused on creating the cave system as a setting for a game, while Woods was interested in making a game and not in replicating the feeling of caving.
Woods's version, released in 1977, expanded Crowther's game to approximately 3,000 lines of code and 1,800 lines of data, growing to 140 map locations, 293 vocabulary words, and 53 objects. Woods also added access controls to the game, allowing mainframe administrators to restrict the game from running during business hours. Woods began working on the game in March 1977; by May his version was complete enough to release, and was soon attracting attention around the United States. Woods continued releasing updated editions in Fortran until 1995. Crowther later said that Woods's bringing fantasy elements earlier into the gameplay was an improvement to his version, though Crowther's daughters also recall him telling them when they were frustrated at puzzles in the game that it was one of Woods's additions, not his.
Crowther did not distribute the source code to his version to anyone else, and it was later believed to be lost until it was rediscovered on an archive of Woods's student account at the Stanford Artificial Intelligence Laboratory in 2005. Woods, however, distributed the code to his version alongside the compiled executable. Woods's 1977 version became the more recognizable and widespread version of Colossal Cave Adventure, in part due to its wider code availability, as it led to several other variants of the game being produced.