One word: Pokemon
I once stayed up till 5:30 in the morning playing that game. Funny thing was, for about 2 days afterward, everywhere I would go, I would hear the music playing in my head, but it wasn\'t just like when you play a game and get a song stuck in your head, I could HEAR the music everywhere I went. It sounded so real, I would think someone else was playing it. There is only one other game that takes that honor: Tony Hawk\'s Pro Skater 2.