EGGG: Automated programming for game generation

by J Orwant EGGG, the Extensible Graphical Game Generator, is an experiment in automated programming By concentrating on a particular domainÐ gamesÐ EGGG allows users to create applications with a minimum of programming effort We codi®ed the similarities among games and game programs into reusable software components that decouple the rules of a game from its implementation As a consequence, users can create games merely by describing the rules to EGGG, which then generates a fully functioning game program In this paper, we survey the design and implementation of EGGG and provide some examples of games that can be created with the system P rogramming is hard But programming for a par ticular domain need not beÐassumptions about the domain can be built into the language and into whatever system (compiler, translator, interpreter, or combination of all three) ultimately turns the pro gram into an executable application Games have several advantages as a domain for au tomated program generation They have the right amount of diversity (not too little, not too much); many games can be easily represented with a small set of rules; and the generated programs need not be perfect to be usable Classic games (poker, chess, tictactoe, rockpaper scissors, and so on) are much more alike than one might imagine, and these similarities were used to create a universal game engine called EGGG , the Ex tensible Graphical Game Generator EGGG is a pro gram that generates programs: designers provide it with the rules of a game, and the rules are rendered into an actual computer game ready for play The Atari 2600 system revolutionized the game in dustry in 1978 because of cartridges; previous sys tems (with the exception of the Fairchild Channel F) were able to play only a static set of games The decoupling of hardware and software was made pos sible by simpler and more ¯exible hardware com ponents We take the decoupling further by creat ing simpler and more ¯exible software components Instead of decoupling hardware from software, EGGG decouples a game's implementation (the ªhard soft wareº) from the rules of play (the ªsoft softwareº) EGGG uses a highlevel language that lets designers describe games in as few words as possible, while still retaining the precision that the underlying engine needs to render the language The language is ex pressive (users can create almost any kind of graph ical twodimensional game) and concise (statements are short and powerful; debugging is easy because users can see the entire game on one page) The design criteria for the EGGG language and en gine follow, in decreasing order of importance: cGame descriptions should be briefcEasy games should be easy to generate, and hard games should be possible to generate cThe EGGG engine should contain as little a priori information about particular games as possible r Copyright 2000 by International Business Machines Corpora tion Copying in printed form for private use is permitted with out payment of royalty provided that (1) each reproduction is done without alteration and (2) the Journalreference and IBM copy right notice are included on the ®rst page The title and abstract, but no other portions, of this paper may be copied or distributed royalty free without further permission by computerbased and other informationservice systems Permission to republishany other portion of this paper must be obtained from the Editor ORWANT 00188670/00/$500 ￾ 2000 IBM IBM SYSTEMS JOURNAL, VOL 39, NOS 3&4, 2000 782 E GGG : Au tomate dprogramming for game gene ration cIt should be easy to create variationscThe EGGG engine and the games that it generates should be portable across platforms cThe games generated by EGGG should be easy to modify cEGGG should not take a long time to generate games, and the games that it does generate should not run so slowly that playability is affected Game categories and descriptions A taxonomy of games was developed for EGGG and is described in detail elsewhere 1Unlike most pop ular game categorizations that focus on the struc ture of the game, or game theoretic categorizations that focus on information and probability, we focus on what matters to a game developer: processWe classify games according to the following attributes: 1 FreneticsÐwhether the game requires quick ac tion, or is timed (used to