I'd always heard of people using this phrase to describe this game, and I figured it was used lightly.  It's just about 1:00 AM, and I've been playing for four hours.  I actually didn't even realize the time.  What's the most amount of time you've played this for a single session?

6 hours. But that's nothing compared to the amount of time I consistently lost in earlier civ games, where a six hour session was considered short, and the norm was around 9 hours without a break (except to grab food/drink or go to toilet).

I've played it roughly nine or so hours straight before.

I can't really remember, but I'm pretty shure I played it at least once for a whole day. Which is 12-14 hours or something.

Back in college, my roomates would just set up the game so when I got home, it was my turn already.

God I didn't sleep from Friday til Sunday.

I haven't played any of the Civ games but I have played Alpha Centauri... I've had my share of "one more turn..." moments.

Bought Civ 4 with Beyond Sword and Warlords recently. Wanted a slightly older game that would run well on my laptop. Can't believe I didn't pick this up earlier, never played a game so addictive.

My sessions are typically not shorter than 3-4 hours, longest was probably about 8 hours, but not sure.