It takes me about 3-4, no more than 5 hours to complete a standard speed immortal game. What about you guys?
My record is one year and three months.
I played a huge map, marathon speed en played 5 turns per day (not including weekends and holidays). I wrote down what I did and made a plan once a week (what cities would produce this or that, what AI-opponent I was going to attack, et cetera).
Just fun to make a sort of written history of my country in Civ5