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_____________________________________ | | | The Generic Adventure Game System | |_____________________________________| (version 1.0) Copyright 1985 by Mark J. Welch Mark J. Welch P.O. Box 2409 San Francisco, CA 94126 (415) 564-1066 (voice) (415) 664-2811 (modem) _____________________________________________________________ | | | The Generic Adventure Game System (GAGS), including all | | source code, object code, and manuals on paper or on disk, | | are copyright 1985 by Mark J. Welch. "Generic Adventure | | Game System" and "GAGS" are trademarks of Mark J. Welch. | | GAGS is distributed as Shareware: if you like the | | program, please become a registered used by sending $15 to | | the author. Commercial use without prior written | | permission is prohibited. See Appendix C for details. | |_____________________________________________________________| The Generic Adventure Game System Copyright 1985 Mark J. Welch Table of Contents PART ONE (PART1.DOC) Introduction & How to Play Files on the disk..............................................1-1 Hardware requirements..........................................1-1 Acknowledgements...............................................1-2 A Short History of Adventure Games.............................1-3 Enter GAGS?..............................................1-4 Other Adventure-Writing Systems..........................1-5 Further Reading..........................................1-5 Quick Start....................................................1-6 How to Play the Sample Game(s).................................1-7 Vocabulary...............................................1-7 Abbreviations............................................1-8 Special keywords.........................................1-8 Nouns....................................................1-8 Noise words..............................................1-8 Prepositions.............................................1-8 Playing the Game(s)......................................1-9 PART TWO (PART2.DOC) How to Write an Adventure Game Why Should I Write My Own Adventure Game?......................2-1 How GAGS Works: A Superficial Explanation......................2-2 A Sequential Account.....................................2-2 How GAGS Works: Another Approach...............................2-5 Rooms....................................................2-5 Specials.................................................2-6 Nouns....................................................2-7 Text.....................................................2-8 PUSH/PULL/TURN/PLAY descriptions.........................2-8 Creatures................................................2-9 Some Last-Minute Notes........................................2-10 Order of definitions....................................2-10 Word Processors (data file format)......................2-10 Diagnostics Mode........................................2-10 Light and Darkness......................................2-11 Command Abbreviations...................................2-11 Creating a Typical Room.......................................2-12 Including Comments in the Data File...........................2-15 (continued) Table of Contents (continued) REFERENCE MANUAL (in PART2.DOC) Introduction...................................................R-1 Opening (Title) Screen.........................................R-1 Structure of the .DAT (data) File..............................R-2 Description types........................................R-2 Nouns....................................................R-3 Rooms....................................................R-4 Creatures................................................R-5 Specials.................................................R-5 Text.....................................................R-6 Page Pauses..............................................R-6 Play/Push/Turn/Pull......................................R-6 INTRO text...............................................R-6 Lights and Darkness......................................R-6 Eating, Drinking, and Dying..............................R-7 Weight and Size..........................................R-7 Scoring/Points...........................................R-7 PART THREE (PART3.DOC) The GAGS Source Code (briefly explained).......................3-1 In More Detail: The Parser.....................................3-3 Possible Source Code Enhancements..............................3-5 Enlarging the Game.......................................3-5 On-Line Help.............................................3-5 Specials.................................................3-5 Adding Verbs.............................................3-6 Multiple Nouns with the Same Name........................3-6 Creature Animation.......................................3-7 Time/Turn Sensitivity....................................3-7 User-Defined Verbs.......................................3-7 Attempts to Reduce the Size of GAGS............................3-8 APPENDICES (APPENDIX.DOC) Appendix A: List of Verbs........................................A-1 Appendix B: Partial Map of Sample Game...........................B-1 Appendix C: Distribution (the Shareware Rules)...................C-1 Appendix D: Other Shareware......................................D-1 1-1 This is the manual for the Generic Adventure Game System (GAGS). You do not need to know anything about programming to play the adventure games on this disk or to develop your own adventure games. Files on the Disk ----------------- Included on the disk are a number of files. If there is a file on the disk called READ.ME or README.1ST, read that file before going further. Please read Appendix C ("The Shareware Rules") before making any copies of GAGS. - ADVENT.COM The file ADVENT.COM is the executable game "engine" program (generated by Turbo Pascal 3.0). - ADVENT.00* Files beginning with ADVENT and ending with numbers are overlay program files, which must be present on the same disk and directory as ADVENT.COM. - *.DAT Files with the extension (suffix) .DAT are data (UNDERGND.DAT) files read by the ADVENT.COM program when it is running; there are several complete adventure games included on the disk in files ending with .DAT. - *.TTL Each file with the extension .TTL contains the (UNDERGND.TTL) title file for a corresponding game file stored in a .DAT file. - *.DOC Documentation for GAGS is stored in files ending with .DOC. These should be printed out and read in the same order as they appear on the disk. Hardware Requirements --------------------- The Generic Adventure Game System requires a computer with at least 256K of memory, MS-DOS 2.1, and at least one disk drive. 1-2 ---------------- Acknowledgements ---------------- I'd like to thank the folks who helped me debug GAGS prior to its formal release. Beta-testing software is usually a dangerous, painful, and unrewarding task; in this case, since the program will be distributed as Shareware, there was no financial reward except a free disk or two. Several people found gamewriting an incentive by itself, while others just wanted to poke around and discover bugs. Many thanks to everyone who helped. In particular, I'd like to thank Stan Heller and Katherine Pyle, each of whom spent many hours actually developing playable games, and each discovering many unexpected bugs and "features." Mike Rauch provided the most eloquent and detailed plea for improvements I've seen. Sue Rosenberg, Neil Rubenking, Andy Meyer, Patrick Herron, Ezra Shapiro, Mike Farren, Mark Lovejoy, and Ctein each offered important bug and performance reports. All of the above (and a few others) provided insight without which GAGS would be far less powerful and useful. All these poor souls got in exchange is a free copy of version 1.0 and my thanks. ------------------------- Structure of This Manual: ------------------------- Part 1 explains how to play the adventure game(s) included on the disk. Part 2 explains how you can create new adventure games by modifying the enclosed data files or by writing your own data files. It also includes a complete reference manual. Part 3 explains how the Turbo Pascal program is structured, and how you can modify it to add features to the Generic Adventure Game System or even overhaul it completely. The source code is NOT included on this disk. It is available separately, to registered users only, for $25; I also require that you sign an agreement that you will not share the source code. Appendices: (A) List of verbs (B) Map of the sample adventure (C) GAGS Distribution Policy (D) Other Shareware 1-3 A Short History of Adventure Games ---------------------------------- You probably realize that there is a whole class or genre of computer games called "adventure games." The genre, of course, is loosely based on role-playing games. Indeed, the Original Adventure and Dungeons and Dragons both became immensely popular at the same time -- the mid 1970's -- on college campuses. The grandfather of all adventure games was called simply "ADVENTURE," and took place in "Collossal Cave." It was written by Will Crowther and Don Woods in FORTRAN. To win the game, one has to capture a bird, dispose of a nasty snake, avoid a dwarf's pointy knives, and figure out what toll a troll wanted to cross a bridge, among many other hazards; the rewards were many but usually had to be sacrificed in order to obtain some other goal. The game was quite successful -- partly because it was virtually the only game available and partly because it was freely distributed over ARPANET -- and was quickly copied onto many large timesharing systems at universities and companies. Many hours were spent translating the game so it could run on many mainframes and microcomputers. Other programmers wrote extensions into the game, adding new rooms, hazards, and treasures. (The Original Adventure is available from Software Toolworks, Pasadena, CA, as well as in a four-game pack called "Golden Oldies, volume 1.") While some programmers were satisfied by solving, translating, or adding to the original Adventure, others saw an opportunity for new games, on microcomputers as well as mainframes. Some -- like Scott Adams at Adventure International -- chose to add graphics to their adventures. Some had very limited vocabularies and tight, simple grammers like the original adventure: you could "EAT BIRD" or "ATTACK TROLL," nothing more complex. Other programmers sought more natural language and more powerful and complex features: Infocom's Zork trilogy -- a variant on the original Adventure -- and that company's many follow-up text adventures (they, and others, accurately call their works "interactive fiction") use a complex vocabulary and permit very long and complex sentences. On the earliest microcomputers -- like the S-100 machines, the TRS-80 Model I and the Apple II -- adventure games were the first programs to be made available because they used only text and were written in standard languages, usually BASIC, and were thus easiest to translate. Several efforts have been made to write "adventure game generators," programs which would ask for input detailing the arrangement of an adventure and then generate a BASIC program for the scenario. Unfortunately, these generators too often were not complex enough to generate powerful adventures, or were too complex to use by someone who didn't want to write an adventure game in the first place. 1-4 Enter GAGS ---------- The Generic Adventure Game System was written in an effort to make writing an adventure game as simple as possible, while still permitting a great deal of flexibility. It _cannot_ be used to write an adventure game with as many complex features as Infocom's. To do so would require developing a complete adventure game programming language, as Infocom has done, and would require adventure-game writers to learn a very complex set of rules. Of course, developing ANY playable, enjoyable adventure game takes time. You need to set up a map, and then type in the valid movements from room to room and the full text descriptions for each room, noun, and creature. While using GAGS is far less complex than writing an adventure game from scratch in Pascal, BASIC, or any other language, it will still take you many hours to write a game using GAGS. Part II explains how you can write your own adventure. There are two clear advantages to the Generic Adventure Game System (GAGS). First, GAGS uses a standard-format text file for its data, and the adventure game can be modified simply by editing the data file with any text editor. Debugging the game involves playing it: as problems are discovered, the text file can be edited and the game re-played. Once a basic game is developed, it can be extended by adding new rooms or special features (much the same way Adventure was enhanced). Second, GAGS is infinitely expandable because the complete Turbo Pascal source code is available. If you decide that another verb should be available, you can add it. If you think the parser is too simple, you can try to patch it -- or completely re-write it. By modifying the source code, you can add new features to the game which aren't available in the basic system. (Of course, modifying the source code could lead to week-long debugging sessions while you try to figure out why this particular procedure is infinitely recursive or why the disk is reformatted whenever you try to move east.) Part III of the manual explains how the source code was written, and suggests a number of modifications that can be made. The complete source code to GAGS is available to registered users for $25, and you are free to make any changes to that code you wish. You can freely distribute any adventure game files you write for GAGS, and you can distribute executable copies of the ADVENT.COM file without paying any royalties, whether or not you've modified it. You may not distribute source code copies of GAGS, even if you've made changes to the program. You are free to distribute lists of the changes, of course; I just don't want people to get the source code without paying for it. 1-5 ------------------------------- Other Adventure-Writing Systems ------------------------------- Pete Levy has posted a copy of the "Levy Adventure Development System" (LADS) on the Games SIG on CompuServe. It's written in BASIC for the TRS-80 Model I and III; I believe versions for other systems exist. Eamon, a public-domain adventure-writing system for the Apple II, is reportedly a good system as well. An enhanced commercial version is also said to be available for about $40. David Betz, author of the XLISP programming language, is also developing an adventure-game programming langauge using a similar syntax. While it will be more complex than GAGS, it will also have more advanced capabilities. Several commercial adventure writing programs are also available. For the Commodore 64, CodeWriter Corporation's Adventure Writer looks like a pretty good product. Electronic Arts' Adventure Construction Set is primarily a graphics/arcade- type system. Another program, Adventure Master from CBS, is getting wide attention but generally poor ratings. --------------- Further Reading --------------- Several books are available on writing your own adventure game: Tim Hartnell, "Creating Adventure Games on Your Home Computer" (in Microsoft BASIC), Ballantine/Random House, 1984. Richard C. Vile, Jr., "Programming your own Adventure Games in (UCSD) Pascal," TAB Books, 1984. Frank DaCosta, "Writing BASIC Adventure Programs for the TRS-80" (Model I/III/IV), TAB Books, 1982. The December, 1980, issue of BYTE magazine contains a number of articles about adventure games. Articles include: "On the Road to Adventure," by Bob Liddil; "Zork and the Future of Computerized Fantasy Simulations," by David Lebling; and "Character Variation in Role-Playing Games," by Jon Freeman. 1-6 ----------- Quick Start ----------- If you've never played an adventure game before, the best way to start to understand how an adventure game works is to play one. Before you can do that, however, there are a few things you should do first to protect yourself. 1. First, make a copy of the original disk that came with this book, and put the original disk in a safe place. That way, if you accidentally damage the disk you're playing with, you can still re-copy the original. To do this, place a formatted, bootable system disk in drive B: and the original disk in drive A:, and type "COPY A:*.* B:" 2. Reboot (Ctrl-Alt-Del), then type "ADVENT UNDERGND" at the DOS prompt. ---------------- If you want, you can play this game as a regular adventure game; below are some hints on how to play an adventure game. If you prefer, you can "cheat" and peek at the map in appendix B and the list of verbs provided in appendix A. You can cheat even more by reading the file UNDERGND.DAT. ---------------- The Generic Adventure Game System requires that five files be on your default disk: ADVENT.COM The game program itself; ADVENT.000 A program "overlay file" ADVENT.001 Another overlay file <filename>.DAT The data file for the game; <filename>.TTL The opening title information. The game will also function more smoothly if you have the following two files on your disk: COMMAND.COM The DOS command interpreter CONFIG.SYS The DOS configuration instructions If you're puzzled, type "ADVENT ?" 1-7 ---------------------------------------------------- How To Play The Adventure Game(s) Provided with GAGS ---------------------------------------------------- ---------- Vocabulary (examples) ---------- The Generic Adventure Game system understands a wide variety of commands, but it is still easily confused. It has a very limited vocabulary, totalling from one to four hundred words. While it can understand some fairly complex sentences, there are some pretty simple sentences it gets confused by. Your commands should generally be in the format: <verb> <noun phrase> <preposition> <noun phrase/object> Some (hypothetical) examples of valid sentences: put the red rock in the small bowl read the poetry book eat the celery throw the battle axe at the werewolf shoot the burglar with the revolver fire the laser pistol at the alien mutant get the book push the red button unlock the file cabinet with the steel key go north southwest turn on the flashlight General Rules ------------- A list of valid verbs appears in an appendix, but you might want to experiment and guess at valid verbs before reading it. The usual directions are understood by the game (N, S, E, W, NE, NW, SE, SW, UP, and DOWN; in some cases, 'enter' or 'exit' might also be appropriate). Other events might also cause you to change location: if you detonate a nuclear warhead, for example, you'll likely be immediately transported somewhere far, far away. You can try to 'take' or 'get' most things that are in a room with you; you can 'examine' or 'look at' most visible nouns as well, whether or not you are carrying them. You can 'drop' or 'throw' anything you're carrying. Eating and drinking are often permitted, but eating strange things is usually foolish. If something seems to be closed or locked, you can try to open or unlock it. 1-8 Abbreviations ------------- To look more closely at something, 'examine' it. The period character ('.') is a synonym for 'examine,' so typing ".book" is the same as "examine book." You can also abbreviate 'examine' as 'ex' (i.e. 'ex book'). The exclamation point ('!') is a synonymn for "attack." To turn out a light, you can 'extinguish' it, and 'extinguish' can be abbreviated as 'ext' ('ext lamp'). Special Words ------------- Certain words have special meanings to the game. 'Brief,' for example, suppresses the automatic printing of room descriptions each time you enter a new room; to return to full descriptions, type 'verbose.' 'Score' will let you see how much progress you've made and will give you an idea how much of the game you've seen so far. 'Quit' will permit you to stop the game and return to DOS. 'Save' will allow you to save the current game status, and 'restore' will restore a previously-saved game. There's no penalty for incorrect words: if the game doesn't understand a word, it gives you another chance and doesn't count the invalid input as a turn. If you try to do something foolish ("Eat chair"), the game counts that as a turn. Nouns ----- While the list of verbs is fixed from game to game, the nouns change every time. One game might be filled with weapons and creatures, while another might contain many keys and locks. Each noun is unique: you won't find more than one "key," but you might find a "brass key," an "access card," and an "entry pass." The game only understands an adjective if it is correctly followed by the matching noun: if "take red flute" is valid, it will not try to guess what you meant by "take red" or "take red instrument" or "take the red one." It will accept "take flute," but not "take blue flute." With some verbs, nouns are optional. For example, "north" is quite clear by itself, and any "valid" words following it will be ignored completely. "Eat" needs a noun of some kind, preferably an edible one. And some things can't be accomplished unless you specify a tool: "unlock padlock" isn't acceptable, while "unlock the padlock with the brass key" is fine. Noise Words ----------- The word "the" is ignored; so are friendly words like "please" and "now." (This way, "please put the red rose in the small vase now" can be understoond, while the game will be quite confused by "Please the sailor.") Prepositional phrases --------------------- In some cases, the preposition need not be followed by a noun ("turn the gas stove on" is fine), but often the game will be puzzled unless you provide one ("unlock the padlock with" just won't do). 1-9 Playing the Game(s) ------------------- As you move around through the game, you'll notice that the game provides a long text description of each room as you first enter it. If you return to the room later, it's merely identified by a short descriptive phrase in brackets. To see the full description again, type "look" or "L". The game doesn't keep these long text descriptions in local memory, but instead reads them from disk each time it needs them. If you don't like this delay, you can suppress the long text by using the "brief" command. "Verbose" will bring them back. You may be unable to find any more rooms in the adventure, even though you know there should be more. Remember that strange actions might be necessary to get from one room to another: in a haunted house, for example, pushing the bookcase aside might reveal a hidden staircase to the dungeon. In a more modern adventure, you might have to figure out how to start and fly a spaceship and fly to another planet, where more rooms await you. In another adventure, you might discover that touching a rock sends you somewhere new.