TI3
I spent most of today (about eight hours) playing a game of Twilight Imperium 3. This is the second time I've played this game and each time it has taken about that long. It's a very complicated game, the rules are about 44 pages long and there is also an extensive FAQ. The first time I played was with four people and this time it was with six (including a modified ISC). I enjoyed the six player game more, mostly due to the increased inter-player activity.
The modified ISC still overly contributed to the win of of the game (but not as much with four players). We played that whoever took the ISC got one point and whoever controlled Metacol Rex got a point. I like the ISC variation proposed in the rules variants. In any case while it is a long game I've had fun playing it both times and would enjoy playing it again with six people.