What made Pong so hard to put down, with just two paddles and a ball?

Pong looks like the simplest game imaginable: two paddles, one square ball, a score. Yet in 1972 it became the first commercially successful video game, and the reasons say a lot about how games are designed. They had little to do with technology. They were small choices that made a bare idea feel good to play.

The game started as an exercise. Atari co-founder Nolan Bushnell gave a new engineer, Allan Alcorn, a simple brief: one moving spot, two paddles and a score. Alcorn had never made a video game. Because he found the basic version boring, he added touches of his own. He split each paddle into eight segments, so that where the ball hit decided the angle it flew away at. That turned a bounce into a skill you could aim. He also made the ball speed up the longer a rally lasted, and reset the speed when someone missed. Every rally built tension, and every miss gave a fresh start.

One design decision was an accident. A defect in a simple circuit meant the paddles could not reach the top of the screen. Alcorn kept it, because it made the game harder and stopped two very good players from rallying forever.

The test was a bar. Alcorn and Bushnell put a prototype in Andy Capp's Tavern in August 1972, and some time later the machine broke down. Alcorn opened it up and found the coin mechanism overflowing with quarters. Bushnell later estimated it earned about 140 to 160 plays a day per console.