Building worlds; games that give you the powers of a god, a president, a billionaire. (The Brave New World of Electronic Games)

Sit in front of a computer screen long enough and it becomes a world in itself. A growing number of game designers are taking advantage of that to create games in which players build self-contained worlds.

"Environment" games give players the opportunity to control some aspect of a world's development, whether ecological, social, or industrial. Maxis' SimCity, perhaps the most famous example of this type of game, provides players with undeveloped land and the tools to turn that land into a thriving metropolis--or a polluted, overpopulated nightmare. Running a growing city is no more easily achieved in a computer world than in reality.

Designer Chris Crawford, whose Balance of Power translated superpower tension into a tense software experience, recently released Balance of the Planet through Accolade. This time Crawford's turf is the global environment itself, with players forced to make choices between ecological concerns and civilization's needs.

Sid Meier, whose MicroProse games such as Red Storm Rising and F-15 Strike Eagle helped define state-of-the-art military simulators, has turned to more peaceful pursuits with Railroad Tycoon. Players are transported to the early days of steam-powered transportation, provided with capital, and challenged to build a successful rail empire.

The team that designed SimCity set themselves the largest of all possible tasks in SimEarth: Create a simulation of an entire world. Their starting point was the Gaia theory proposed by James Lovelock and Lynn Margulis, which, put very simply, views a planet as a single organism. In the game this vision becomes a living electronic entity as you guide the transformation of worlds--Earth among them, but also Mars and others--from primordial matter to thriving ecospheres.

>From macrocosm to microcosm, there's a school of thought that argues that electronic life can be created, or at least considered. Cellular automata--software representations of living, evolving life forms--are already replicating in computers around the world, producing some very surprising offspring, Mathematician and science-fiction writer Rudy Rucker has created one of the most engaging cellular automata programs, called, appropriately enough, Rudy Rucker's Cellular Automata.

What all of these programs have in common is a sense of consequences, of the effect of decisions and actions on a larger world. Make the wrong decision and you have to live with its ramifications throughout the rest of the game. Make the right decision and watch its consequences flower. The best world-building games give latitude to "right" and "wrong" decisions, just as the real world does.

There's fine line, obviously, between world-building games and educational software, but it's a line that many designers happily tread. By making learning "painless," environment games pass along quite sophisticated lessons to their players. Because the programs are malleable--your worlds reflect your choices--you are your own teacher. That's a learning experience to be savored--and enjoyed.