As the title says: What game did you spend the most time on in total? For me, this question is surprisingly hard to answer given the lack of time keeping in older titles. I think it's probably a Blizzard RTS as I spend a lot of time in Warcraft III (including DotA), Starcraft and Starcraft 2. However, Diablo 2 is a strong contender as is Baldur's Gate 2 as multiple play throughs quickly rack up a lot of time.