This is a simulation of the 1972 Atari game Pong at a circuit level. The original Pong did not have any code or even a microprocessor. It was a circuit, implemented mostly using digital logic chips, with a few timers and other analog components.

Here is a link to full schematics. Thanks to whoever made this. I just found a few issues with it. The CLK input to the 7474 on page 2 should be HRESET, not CLK. Also some of the nodes are inconsistently labeled.

Also see Reconstructing Pong on an FPGA by Stephen A. Edwards, which describes everything about the Pong circuit in exhaustive detail. This was an enormous help to me in understanding the schematic; huge thanks to him.