Today’s computers make it vastly easier for scientists to build these models. They have also allowed researchers to study evolution by building digital organisms. Scientists at Michigan State University and the California Institute of Technology, for example, have developed software called Avida that allows tiny computer programs to behave like real organisms. They make copies of themselves and mutate (randomly changing lines of programming code).

As the programs process more information in more powerful ways, the mutations are favored by a digital version of natural selection. The Avida team has published a string of papers in leading scientific journals on their experiments, testing ideas about complexity, mass extinctions and even the evolutionary benefits of sex.

Computers have also made it possible for scientists to build simple simulations to help people understand the principles of evolution. This year, for instance, Ralph Haygood, a postdoctoral researcher at Duke University, built a Facebook application called Evarium that lets users watch flowerlike creatures drift around a box, attracting one another with their colors. They mate and shuffle traits in their offspring, which then go through the same cycle. Players can control how quickly traits mutate and how strongly the organisms are attracted to some traits and not others. Or they can just watch the creatures change each time they open their Facebook page.

Mr. Wright came to the challenge of an evolution game with a long track record of simplifying complex systems without losing the feel of reality. He first came to fame in 1989 with SimCity, a game that allowed players to build and oversee a city. He simplified the workings of cities so that the slow personal computer of the late 1980s could simulate them. But he included enough feedback loops between elements of cities — like tax rates, incomes and traffic jams — to give SimCity the unpredictable complexity of real cities.

Mr. Wright followed the success of SimCity with a string of open-ended games, like SimAnt (a simulated ant colony) and SimMars (a simulated Red Planet players could make habitable). Around the time he released the Sims, he began to contemplate an all-encompassing game. At first, he called it SimEverything.

The game, which he eventually renamed Spore, would give players an experience of life and the universe across billions of years, from microscopic creatures to interstellar civilizations. “There were deep motivations in the early phase from the work of a lot of evolutionary biologists, like Richard Dawkins and Edward Wilson,” Mr. Wright said in a telephone interview.

Mr. Wright wanted Spore to communicate some of the grand patterns of evolution. But he did not want players to spend a million years waiting for something interesting to happen. He also did not want the game to look like an abstract cloud of drifting spots.