Don't tell my boss, but when I have ten minutes of downtime at work, I've been playing Ultima VI. When CD-ROM drives came out, my dad upgraded our PC with one and it came with a disc containing Wing Commander and Ultima VI. We played the hell out of Ultima VI for years without ever really knowing what we were doing, just running around getting all kinds of sweet equipment and gobs and gobs of money, but never advancing the quest. Since I've figured out better how one plays and advances through an RPG in the intervening decades, Ultima VI has been on my to-do list for years, especially after I played Ultima V: Lazarus - a conversion mod for Dungeon Siege that brings the eponymous game to a (somewhat) modern engine. There's also the Ultima 6 Project, which does for Ultima VI what Lazarus did for Ultima V, but that's not really an option at work, especially since my Dungeon Siege discs got scratched up and don't work anymore.
I've only put about an hour into it so far and I've got a lot of character advancement to do, but I've already advanced the story further than I ever did in those tens, maybe hundreds of hours I spent playing it as a kid.