Go through the Ben Eater channel on YouTube. It'll get you up to speed with early 80s computing. Computers quickly stop feeling like magic after you grasp the basics. Watching him build a VGA card should be enough to intuit how Pong was made.

One which gets mentioned often is NAND 2 Tetris, which starts with basic logic gates and progresses to produce a simple computer:

https://www.nand2tetris.org/

Also try nandgame.com