This is the schematic diagram for the original arcade version of Pong as the original digital video game. Pong used a all digital circuit to make the sound, controls, and graphics. This is not a software processor like the Xbox 360 or whatnot, but a collection of 66 discrete chips that perform a single function to be interconnected to produce the game we love.
This is very hard to read and obscures many details, but of course this is how all games back then were mapped out so they were quite used to it. Here’s the digital layout in modern software terms:
In 1972 this would have all been done by hand with pencil and paper, could you imagine being a game designer back then?