Just had to vote with time spent playing the games - close choice between Civ, Populous and Settlers.
In the end it just had to be the one game that STILL gets me switching the A4000 on, cranking up the speakers and playing just one more time, and that's Settlers. Stopped playing GTAIII last night, went upstairs and decided to have a quick 1/2 hour before going to bed... god I'm sad
Populous still holds the lenth of time for one sesh at 11.5 hours - started 6pm, and a couple of hours later.... checked the clock to see 5:30am!!!! but settlers aint far behind (8.5 hours) and Civ's up around 7 - 8 hours.