Tetris. It's the best game ever.
Seriously though, Tetris has had a long lasting effect on the human race.
Have you ever been loading your car with grocery or whatnot and you think to yourself, how can I position this stuff better?
Then your teenage mind kicks back in and you realize...I've faced this situation before, with some snazzy music in the background.
The greatest thing about Tetris? It's math based, so you're learning while you're having fun.
Tetris has stood the test of time, originally starting on the PC and is now even featured as a game on IPod's.