[jameskilton]

Tetris is my go-to and my #1 recommendation when someone asks how to get into game programming. It's such a simple game conceptually but surprisingly difficult to actually implement.

[lucideer]

I've never tried building a Tetris but if it's as difficult as you say, I guess this must be doubly impressive https://gist.github.com/aemkei/1672254

[throwaway2016a]

It all depends on how much of the gameplay mechanics you implement. That implementation has very few of the gameplay mechanics.

Still very impressive none-the-less... I bet most coders couldn't do tic-tac-toe in that little code.