Artificial Intelligence in Games

There are many types of computer programs that use AI. Market simulators, logic systems, and economic planners are some of the different fields of computer software that rely heavily on elements of artificial intelligence. These elements include situation calculus, tree searching, problem solving, and decision-making. But one genre of software programming has been slowly borrowing more and more from the field of AI is video gaming. Video games have gone through drastic improvements in the past ten years. It seems as if Moore’s law applies to video games as well as processor speed. Video games seem to get twice as complex in some ways every eighteen months. As these games get more complex they also get more interesting and engaging. Video games are no longer just a distraction from work or a thirtyminute escape from reality. They are becoming an artistic form of expression for the programmers and developers and a serious hobby and undertaking for the players. One relatively new game that shows this drastic advancement in the complexity and beauty of video games is “Black and White” by Lionhead Studios. “Black and “White” has made its mark on the video gaming industry through its remarkable implementation and manifestation of artificial intelligence.

History of Video Games and Their Use of AI
Physicist Willy Higinbotham created the first video game in 1958. It was called “Tennis For Two” and was played on an oscilloscope. The first game to run on a computer was “Spacewar” by Steve Russell from MIT. The graphics were ASCII characters and it ran on a Digital PDP-1 mainframe. In 1970 the future founders of Atari, Nolan Bushnell and Ted Dabney released the first video arcade game, “Computer Space”. In the next ten years companies such as Atari, Coleco, and Magnavox all released home video game console systems. In 1980, Battlezone, the first 3-dimensional game ever, was released. It went on to be used by the US government for the training of military forces. Four years later, the Nintendo Entertainment System was released, marking the beginning of the modern gaming era. Home computers were starting to become practical and popular. Video games designed for home computers started being developed. The fact that home computers had more storage and computing power than cartridge-based console systems allowed for more complicated games. The console industry caught back up in 1995 when Sony brought the PlayStation to the United States. It was the first practical CD based system and a huge step forward. Currently, both console systems and computer games are pushing the limits of modern processors. Real-time 3D rendering, movie-quality video and sound, and intelligent computer agents all continue to amazing gamers worldwide [1]. The history of artificial intelligence in video games dates back to the midsixties. Before that, games were either two-player (meaning that there was no computer opponent) or any non-human objects were hard-coded. An example of hard-coded video game objects are the little aliens in “Space Invaders” that swoop down at the human player. The human player must shoot the aliens before they reach the bottom of the screen. The manner in which these aliens move is explicitly coded into the game and is not determined at runtime by any precepts. The earliest real artificial intelligence in gaming was the computer opponent in “Pong” or variations thereof (of which there were many). The computer paddle would do its best to block the ball from scoring by hitting it back at the user. Determining where to move the paddle was accomplished by a simple equation that would calculate at exactly what height the ball would cross the goal line and move the paddle to that spot as fast as allowed. Depending on the difficulty setting, the computer might not move fast enough to get to the spot or may just move to the wrong spot with some probability. For a long time no video game AI was not much more intelligent the “Pong” AI. This was because the games were relatively simple and most often played with a second player instead of a computer opponent. Atari sports games AI agents were basically goal-oriented towards scoring points and governed by simple rules that controlled when to pass, shoot, or move. The advent of fighting games such as “Kung Foo” for Nintendo or “Mortal Kombat” for Sega Genesis saw only a slight improvement in AI. The moves of the computer opponents were determined by what each player was currently doing and where they were standing. In the most basic games, there was simply a lookup table for what was currently happening and the appropriate best action. In the most complex cases, the computer would perform a short minimax search of the possible state space and return the best action. The minimax search had to be of short depth since the game was occurring in real-time. Real-time game play has always been major setback for AI in video games. There is very little time to compute actions and possible future states when the action never stops. The last ten years has seen great strides in the field of AI in gaming. Most of these strides have been made in computer (as opposed to console) games because of their raw computing power and memory capacities. Currently, driving games like “Nascar 2002” have computer controlled drivers with their own personalities and driving styles. Pass one of these guys while they are having a computer-controlled “bad day” and they will be riding your bumper for miles, trying to take you out. Strategy games like “Warcraft 3” call for users to create an army to defeat one or more computer-controlled villages with armies of their own. These villages will form alliances, scout surrounding areas, and devise appropriate battle plans to do their best to be the last village standing. “The Sims” has reinvented artificial life in gaming. The game starts with the user controlling one person. Eventually the character may marry and then the user can control the spouse also, and then the children. These “people” are wonders of AI. They all have their individual characteristics, wants, and needs. They have the ability to fall in love, make friends, enemies, become hermits, strive for more in life, etc, and will act on their feelings at will. But, there is one recent game that yields an even more impressive use and understanding of artificial intelligence than all of the games listed above.

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