In the beginning (about 30 years ago), geeky college students in the United States stole into engineering buildings at night and turned huge and expensive mainframes into playgrounds.

They created games like "Lunar Lander." It had no controlling keys or visuals; output was successive lines of printed text that told the player the velocity, altitude and fuel remaining in a landing module they were trying to deposit on the surface of the moon.

The mainframe games were primitive, but they and their successors fired the imagination of a whole generation of students who could easily have become engineers or physicists.