Everything there is to know about NES Tetris

http://meatfighter.com/nintendotetrisai/

When I was a kid, I kept track of the pieces I received in Tetris on a piece of paper, because I was convinced that the in game stats were lying (they weren't).

This guy wrote 25,000 words about the inner workings of Tetris (including an interesting RNG, which is actually truly random in practice).

Even if you don't understand or care about the technical details I recommend you skim through it, as there were a lot of interesting items.