Chapter 2

The First Text-Based Adventure Game: Colossal Cave





Willie Crowther liked to crawl around in caves. Periodically, he went to Kentucky to join other amateur spelunkers in exploring Bedquilt Cave, a huge cavern connected to Mammoth Cave. Crowther used the computers where he worked, at Bolt Beranek and Newman (BBN) in the Boston area, to store topographic data and produce maps of the cave. In l975, when he couldn't go anymore to the caves in Kentucky, he used Bedquilt Cave as the setting for a spelunking simulation, in which he could move from chamber to chamber in the cave by typing commands to the computer. In response to his movement commands, the program printed a textual description of each chamber as he entered it. He could also carry "objects" from chamber to chamber in the cave, pick up new objects found along the way, and drop carried objects so that they would be left behind when he moved to a new chamber. Crowther made the program into a game by defining some objects as treasures, and putting these treasures behind obstacles like chasms and giant snakes. The player needed to find and use other objects in the cave to get past the obstacles and claim the treasures. The game had about a dozen objects and 40 rooms. He called it Adventures..

The design of Adventures was influenced by Dungeons and Dragons , a non-computer fantasy role-playing game which Crowther had been involved in playing. In Dungeons and Dragons, a small party of characters explored an unknown subterranean labyrinth full of treasurers and monsters. Each character, who might be a magic-user, fighter, cleric, elf, or thief, was controlled by a human player. A character had a name, and attributes of strength, intelligence, wisdom, constitution, dexterity, and charisma. A character carried along with him supplies, weapons, armor, magic potions, and other useful objects. The party moved through the dungeon, mapping it, searching for secret doors, examining (possibly booby-trapped) treasure chests, and battling monsters. The unknown layout of the dungeon, and the locations of various perils and windfalls, were presided over by a person called the "Dungeon Master." Game play was a dialogue between the exploring players and the Dungeon Master. The Dungeon Master told them about their immediate surroundings and the results of their actions. He used a map of the dungeon which was kept hidden from the players. Adventures was Dungeons and Dragons for one player (a "solo dungeon") in which the computer was the Dungeon Master.


Crowther let the player direct the game with English nouns and verbs. He chose this natural language input, rather than a complicated, formalized command language, because he wanted to make a game that would not intimidate non-computer people. He also designed the game for his kids.


Crowther made the program available to be played on the ARPAnet, one of the first computer networks. The ARPAnet linked university computer science departments and other research institutions across the United States. Don Woods, at the Stanford Artificial Intelligence Lab in California, played the game over the ARPAnet. Woods was intrigued. To get the program's source code, he tracked down Crowther (who had by then left BBN) by sending a message to every site on the ARPAnet. He located Crowther, got a copy of the program, and began playing with it.


Don Woods greatly expanded the game, adding many new rooms, objects, commands and treasures. Whereas Crowther's network of chambers really did describe Bedquilt Cave in Kentucky. Wood's additions were completely fanciful, and owed more to Tolkien's Lord of the Rings trilogy than anything else. (The game's name lost its final "s" somewhere along the way to become, simply, Adventure.). The graduate students working with Woods at the AI Lab followed the development of Adventure with avid interest. They tested their wits against the game's puzzles. As the game developed, feedback from this community of players let Woods make sure that his puzzles were solvable, and let him provide humorous responses for often-tried commands. Wood's roommate, Bob Pariseau, who was, like Woods, also involved in the computer industry, helped with the development of the game. As had been the case with Spacewar at MIT, the young graduate students responded with instinctive fascination to Adventure. Many of them explored the space of rooms and objects within the game, and a few were inspired to explore the very idea of an adventure game -- that is, to write their own games. The responses of the computer science professors working at the AI Lab ranged from mild interest to outrage at the diversion of resources to such a frivolous end.


Woods made the game accessible on the ARPAnet so that his friends at MIT could play it, and he left for two weeks vacation. On his return, he found that the computer at the AI Lab had been swamped with people connecting over the network to play the game. Playing Adventure was soon restricted to nights and weekends.


Crowther had written his Adventure program in FORTRAN, a computer language universally available on scientific and commercial computers. Wood's additions were also in FORTRAN. The program was therefore easily transportable to other computers. In 1977, Woods gave the source code to Ken Harrenstien, who got it running at the MIT Artificial Intelligence Lab. The result there was that "no one got any work done for a week." Requests for copies began pouring in. Woods wrote a few pages of notes about adapting the program to various computers, and turned it loose. Adventure spread rapidly across the country, first over the ARPAnet, and then to computers in hundreds of companies. Releasing the source code did have the advantage that Woods could not get in trouble at Stanford over computer time being wasted on other people's computers. Looking back, Woods said that releasing the source code was "done deliberately, though perhaps not with full understanding of what would ensue."


Adventure became wildly popular among computer people in 1978. Before the infatuation with that particular game had quite worn off, adventure games with new puzzles, on new themes, were springing up all over.




A Text Dialogue


Adventure was a dialogue between the player and the computer. It began like this (the player's commands are in BOLD CAPITALS):



Welcome to Adventure!! Would you like instructions?




Somewhere nearby is Colossal Cave, where others have found fortunes in treasure and gold, though it is rumored that some who enter are never seen again. Magic is said to work in the cave. I will be your eyes and hands. Direct me with commands of l or 2 words. I should warn you that I only look at the first five letters of each word, so you'll have to enter "northeast" as "ne" to distinguish it from "north". (Should you get stuck, type "help" for some general hints. For information on how to end your adventure, etc., type "info".)


This program was originally developed by Willie Crowther. Most of the features of the current program were added by Don Woods (DON @ SU-AI). Contact Don if you have any questions, comments, etc.


You are standing at the end of a road before a small brick building. Around you is a forest. A small stream flows out of the building and down a gully.



At this point the program paused, waiting for a command from the player. If the player typed the command




then the program responded


You are inside a building, a well house for a large spring.


There are some keys on the ground here.


There is a shiny brass lamp nearby.


There is food here.


There is a bottle of water here.


The keys, lamp, food and water were objects which could be picked up and carried to other places.








The objects which the player picked up stayed with him as he moved.



You're in front of building.



You are currently holding the following:

Set of keys

Brass lantern


The player often used compass directions to move from place to place.



You are in a valley in the forest beside a stream tumbling along a rocky bed.



At your feet, all the water splashes into a 2-inch slit in the rock. Downstream the streambed is bare rock.


You are in a 20-foot depression floored with bare dirt. Set into the dirt is a strong steel grate mounted in concrete. A dry streambed leads into the depression.


The grate is locked.



You can't go through a locked steel grate!


You're outside grate.


The grate is locked.


The locked grate was an obstacle that prevented the player from getting beyond it. The player was confronted with a puzzle here. There was a way of getting past the locked grate by performing some particular action, sometimes using a particular object. The problem was to figure out which action, and which object. The player might try



It is beyond your power to do that.


or perhaps



Sorry, I don't know the word "PRY".


Asking for help, as suggested in the game's initial instructions, defined the rules of this guessing game a little bit better.



I know of places, actions, and things. Most of my vocabulary describes places and is used to move you there. To move, try words like forest, building, downstream, enter, east, west, north, south, up or down. I know about a few special objects, like a black rod hidden in the cave. These objects can be manipulated using some of the action words that I know. Usually you will need to give both the object and action words (in either order), but sometimes I can infer the object from the verb alone. Some objects also imply verbs; in particular, "inventory" implies "take inventory", which causes me to give you a list of what you're carrying. Some objects have unexpected effects; the effects are not always desirable! Usually people having trouble moving just need to try a few more words. Usually people trying unsuccessfully to manipulate an object are attempting something beyond their (or my!) capabilities and should try a completely different tack. One point which is often confusing to beginners is that, when there are several ways to go in a certain direction (e.g., if there are several holes in the wall), choosing that direction in effect chooses one of the ways at random; often, though, by specifying the place you want to reach you can guarantee choosing the right path. Also, to speed the game you can sometimes move long distances with a single word. For example, "building" usually gets you to the building from anywhere above ground except when lost in the forest. Also, note that cave passages and forest paths turn a lot, so leaving one place heading north doesn't guarantee entering the next from the south.

Good luck!


The obstacles in Adventure were logical puzzles. The nature of an obstacle usually provided a clue to the means of getting past it. For example, faced with a locked grate, the player often tried



You have no keys!


This response suggests that it might be worthwhile to go back and get the set of keys dropped outside the building.



You're in front of building.


There are some keys on the ground here.






You're outside grate.


The grate is locked.



The grate is now unlocked.



You are in a small chamber beneath a 3x3 steel grate to the surface. A low crawl over cobbles leads inward to the west.


The grate is open.


The solution to the locked grate obstacle was twofold: to have the keys-object and to give the command "UNLOCK." This was typical of the puzzles in Adventure. The non-treasure objects in the game all functioned as tools to get past obstacles. Some of the treasures, too, served as tools.


Going further into the cave turned up some interesting objects.



You are crawling over cobbles in a low passage. There is a dim light at the east end of the passage.


There is a small wicker cage discarded nearby.



It is now pitch dark. If you proceed you will likely fall into a pit.


This darkness was another obstacle, another puzzle. Solving it revealed that


You are in a debris room filled with stuff washed in from the surface. A low wide passage with cobbles becomes plugged with mud and debris here, but an awkward canyon leads upward and west. A note on the wall says "MAGIC WORD XYZZY".


A three-foot black rod with a rusty star on an end lies nearby.



You are in a splendid chamber thirty feet high. The walls are frozen rivers of orange stone. An awkward canyon and a good passage exit from east and west sides of the chamber.


A cheerful little bird is sitting here singing.


There were indeed uses for the wicker cage, the rod with the star on the end, the magic word, and the cheerful little bird. Deeper in the cave were fifteen treasures, hidden within a network of more than a hundred chambers. The player's goal was to gather treasure, and to do that, he needed to explore and map the cave, and experiment with the various objects in order to discover their functions. The game gave the player a powerful impression that he was exploring an unknown, mysterious world.



Direction Verbs, Action Verbs, and Nouns


The structure of the program for Adventure was hinted at when it told the player


I know of places, actions, and things.


The program recognized three types of words: direction verbs, action verbs, and nouns. Direction verbs were used to move through the network of places that comprised the world of Adventure. Both place names (like "BUILDING" or "GRATE") and true direction words (like ''EAST" or "UP") were considered to be direction verbs, along with some intermediate cases (like "ENTER" or "DOWNSTREAM"). Each place had some descriptive text associated with it which was printed when the player moved there.


You are at one end of a vast hall stretching forward out of sight to the west. There are openings to either side. Nearby, a wide stone staircase leads downward. The hall is filled with wisps of white mist swaying to and fro almost as if alive. A cold wind blows up the staircase. There is a passage at the top of a dome behind you.


For brevity, places also had short descriptions which were used when a player had already visited a place before.


You're in Hall of Mists.


Nouns corresponded to objects. The defining characteristic of objects was that they could be carried from place to place. Thus each object had a location. Besides location, each object had a state, which affected the description of the object. For example,


There is a shiny brass lamp nearby.


described the brass lantern, which, however, when it had been lit, looked like this:


There is a lamp shining nearby.


When an object was being carried, it was given a very brief description in the inventory list


Brass lantern


which did not distinguish among its various states.


Action verbs changed the states of objects ("LIGHT LAMP"), handled picking up and dropping objects, and performed other functions. Whereas the places and objects in the Adventure program were defined by tables giving their descriptions and other attributes, action verbs were all handled by special purpose code. (The program consisted of a main program of about 2000 lines of FORTRAN, another l000 lines of subroutines, and 2000 lines for the data base that defined the places and objects.) Most of the action verbs worked in conjunction with particular objects, and had the purpose of getting past particular obstacles.



Active Creatures


Many menacing creatures were encountered in playing Adventure, but most of them were passive, only blocking the player's progress, and could be better thought of as obstacles.


A huge green fierce snake bars the way!


However, there were two types of creature that moved around, actively harassing the player: dwarf and pirate. A creature was best considered to be a type of object which moved around on its own, initiating actions. Dwarves were prone to show up at unpredictable times, and were rather unfriendly.


There is a threatening little dwarf in the room with you!


One sharp nasty knife is thrown at you!


It misses!


In Crowther's version of Adventure, dwarves followed a fixed path through the cave; Woods let the dwarves do a random walk, so that they could end up in any part of the cave. However, this introduced a problem: there were a couple of mazes ("of twisty little passages") in the cave which were easy to get into, and hard to get out of by random wandering. These mazes tended to act as dwarf-traps, so that if the unfortunate player ever did blunder into one, he was quickly assaulted by several dwarves. Woods therefore fixed the dwarves' wandering procedure to avoid the mazes unless the player was in one of them.


The pirate wandered around aimlessly, like the dwarves. (There were several dwarves, but only one pirate.) When the pirate ran into the player, he stole treasure from the player.


Out of the shadows behind you pounces a bearded pirate!

"Har, Har," he chortles, "I'll just take all this booty and hide it away with me chest deep in the maze!" He snatches your treasure and vanishes into the gloom.


The pirate was implemented in the program as a dwarf with special behavior.



Gathering Treasure


The goal in Adventure was to gather treasure, thereby scoring points.


To see how well you're doing say "score". To get full credit for a treasure, you must have left it safely in the building, though you get partial credit for just locating it.



If you were to quit now, you would score 59 out of a possible 430.


The scoring system clearly advertised when undiscovered treasures remained and served as a yardstick against which the player could measure his progress.


Most of the game's puzzles had a treasure lying just beyond.


There is a large sparkling nugget of gold here!


Gathering treasure was a consistent fantasy that united the diverse puzzles of Adventure. Solving the puzzles was the real challenge of the game, but there was something satisfying about going and grabbing the treasure after an obstacle had been overcome.



Characteristics of Colossal Cave


Adventure was a game of exploration and problem-solving in a fantasy world. To explore is to travel into unknown regions, and so the map of the fantasy world functioned as a space through which the player could explore. It is important that the game world could not be seen all at once. If this had been so, moving through the world would expose no new information, hence there would be no exploration.


Exploration was encouraged in Adventure. A player nearly always drew a map to help navigate through the cave. Besides exploring the space of places, the player also explored the space of verbs, seeking to discover what various objects were good for. (It could be frustrating. Adventure was called a "guess-my-command game" by some.)


Adventure was an elaborate logical puzzle. The active dwarves and pirate enlivened the game and avoided total predictability, but the bulk of the game was still passive, waiting to be figured out. It was really more of a puzzle than a game, since once a player solved it, he was done. Asked if he had been part novelist when he created Adventure, Woods replied, "A novelist -- no; an artist -- perhaps; a logician -- certainly."


The "plot" of Adventure depended on choices made by the player. (It might be more accurate to say that the player discovered the true plot -- the solutions to the puzzles -- in the course of playing the game.) A truly interactive narrative like this had never been seen before. The novelty of this interactiveness made it easy to overlook the more ordinary merits of the narrative itself. The writing was good in Adventure. The use of language was precise and colorful. The fantasy setting of Adventure was eclectic, containing magical beings and objects, monsters, and modern machines.


Adventure was full of humor. While Woods was developing the program, people were playing it at the AI Lab, so that he got plenty of feedback about the phrases that people were likely to try in various situations. Some of these often-tried commands, even though they didn't get past any obstacles, did elicit their own special replies from the program, so that the program seemed to comment upon the player's attempted solutions with a friendly sarcasm.



Good try, but that is an old worn-out magic word.


Or, in another situation


There are a few recent issues of "Spelunker Today" magazine here.



I'm afraid the magazine is written in dwarvish.


Wood's Ph.D. dissertation in computer science was "Traversing Planar Graphs." This topic fell into graph theory, an accepted branch of computer science. In developing Adventure, Woods was helping to create a new genre of computer games, and, in fact, a new form of art. It is ironic that in the eyes of most computer science professors at the time, computer games lacked the "seriousness" they deemed necessary for true research. This is a commentary on the academic world, and its relation to innovation and creativity. It permits "serious" creativity. Woods probably could not have written his thesis on "Getting Past Huge Green Fierce Snakes, and Other Logical Puzzles."


Adventure could stand alone on its own popularity, but its greatest significance was in establishing a new genre of computer games. The very existence of Adventure made it obvious, as it must have been with the first novel, that many more examples of this new form could be created, in different settings, with different characters. Inevitably, it was imitated, and a whole legion of adventure games appeared. The first ones inherited the text dialogue style of the original Adventure, and later mutations embraced graphics and animation.




Copyright 1983 Warren Robinett. All Rights Reserved.