People always look for a challenge when they want to play a game, and whole organisations have been formed in order to provide their members with challenging opponents to play against. Countries have national chess ladders and scoring systems, all designed to put more excitement into the game by reducing the certainty of a win for experienced players and giving "newbies" other people to talk to while they learn.

People like to compete in all sorts of different sorts of games, whether mental and rules-based (politics and law!), physical (rugby, soccer, cricket, baseball and many many others!), symbolic (chess), accuracy based (pick-up sticks) or whatever else. In terms of board games, the oldest would have to be chess, in its many forms - Chess, Chinese Chess, Japanese Chess, and various others.

Chess is often considered a test of intelligence; a chess game being where two people pit their intellects against each other in a fiendishly difficult game. Chess is based on several relatively simple possible movements for six different pieces (king, queen, rook/castle, knight, bishop, pawn) on a board of eight by eight squares. However, this does not make the game itself simple as the number of possible combinations of moves over the length of a game is nearly infinite, and thus impossible to memorise.

Most of the time people don't have somebody else to play with when they want to practise their chess game for hours on end, so they turned to computers. Computers have been getting very good at chess recently, and recently beat World [human] Chess Champion Gary Kasparov (see his homepage at Club Kasparov).

With games as complex as chess, it becomes impossible to store a record of every possible move and simply regurgitate the correct response to any attack by an opponent, so other systems must be used - artificial intelligence must begin to be used rather than just a large database of moves.

(For more on chess, see the page about paranoia and world domination.)

Some are, and others aren't ... People would get bored if they continually beat all the enemies in one-on-one games such as MK, so enemy characters must become more and more intelligent. Often games just increase the number of enemies to attack or make their hits more powerful instead of increasing their intelligence. A good example of this is the very popular strategy game, WarCraft II, by Blizzard Software. The computer has only a single level of intelligence, but levels become steadily more difficult to finish due to their landscape, the number and placement of enemies, and a decrease in the amount of available resources for players to use.

Games which involve large levels and simulated areas of landscape such as this tend not to have particularly advanced combat intelligence as it is unnecessary. A crowd of goblins has no need of individual strategies for each goblin, as the force of the whole crowd rushing into a player village and attacking everything that moves is sufficient to challenge someone enough!

Well, the simplest monsters follow you around by moving directly towards you (and, of course, getting stuck by any walls that they could walk around if they were more intelligent) and attack you when they get close enough. Others stay still or move around, firing missiles at you. Game guard towers tend to be stationary, firing at whatever walks past.

The most complex-looking monsters would be those who can form a plan and attack in formation, build walls and various other constructions. However, these are probably just written with a few stored strategies that they can pull out on demand.

Probably the most advanced monsters are those who can run away. Most of the time, monsters and other enemies in games don't run away at all. It's easier to have monsters just continually attacking than to have to make them think about whether they're in a good situation.

Monsters in ID Software's famous Quake run away and hide behind pillars and other obstacles by virtue of their own individual programs, written in a C-like language, inventively called Quake C. Monsters in Blizzard Software's recent release, Diablo, know how to attack in formation and run away when it looks like they're going to be defeated. Interestingly enough, some less intelligent monsters will run away as soon as you kill one or two of them (they are [artificially] scared of you!) while the more powerful monsters are more confident and do not pull back as much.

The most interesting game AI that I've seen is on the science fiction arcade/strategy/adventure game, Star Control II. You are placed on a map with a large number of stars, and there are alien races living on many of the planets orbiting these stars. When you orbit a planet, you can talk to aliens or attack them. When you are moving through hyperspace, a few simple rules appear to govern the movement of other ships: If you are within another race's territory, ships follow you (to either attack you or talk to you, depending on that race's disposition towards you at the time) and otherwise they will either move on their way or attack, depending on how aggressive they are.

But that's not the interesting bit. The behaviour of alien ships in combat is what really deserves mentioning, not the simple logic of ships in space. Once you attack a ship, the game switches into its one-on-one combat mode. There are around 25 different types of ship, and each of these has a strategy for fighting against each of the other ships. Each ship has a different weapon and special ability (such as jumping away through hyperspace to another part of the screen, radiating a huge corona out to destroy obstacles, draining enemy ships' crew and more) and thus the strategy for fighting against long-range and short-range ships, as well as combating the 25 special abilities, must be very complex. Everything is undoubtably logical (programmed into the game by its designers, rather than learnt by a "true" AI system) but it is very impressive nonetheless. Are there 600 (25 x 24) different strategies programmed into the system? Unlikely, considering the small size of the ship data files and the fact that real people programmed all this. But if not, then what? Try playing it and see if you can find out ;-)