KOTOR 1 and 2 are easy choices for me in this topic. I could not stop playing them. FFVI and VII did it for me too. And I'm pretty sure Xenogears did too. They're just that type of game for me. Other than that um... The Baldur's Gate games (for PC, not console). Hmm... I destroyed my Saturn by playing 12-hour sessions of Dragon Force. And when I was a kid I stayed up many a summer night with Shining in the Darkness and Shining Force