Zookie: What game could you play for 8 hours straight?
And two follow up questions
What game should you play for 8 hours straight?
What game have you play for 8 hours straight?
Back when these gaming experiences were new: Betrayal at Krondor, Ultima VII, Diablo, Wing Commander games, particularly Privateer 2, Fallout, Fallout 2, Baldur's Gate 1/2, Planescape Torment, Icewind Dale 1/2, Arcanum, Freelancer, VtM: Bloodlines, and especially Civilizaiton II and Sid Meier's Alpha Centauri (with and without the expansion pack). All of these I had a least one 8-hour session at one time or other, back when my time was cheap and patience enduring.
I'd add Thief 1/2 to the list, except I only played those games at night, and well, four or five hours was typically the max so I'd get *some* sleep.
Nowadays I never game for that long. Usually just an hour or two, in spurts every few days, if that.