Favorite Board game of all time?

Risk has always been my favorite - I can remember epic 5-6 hour games in college. Whereas with the variant of Monopoly known as Drinking Monopoly - where you could pay debt off with shots or mixed drinks - we usually couldn't make it past 30 minutes or so before forgetting all decorum.

Outside of either of these, Strat-O-Matic football ruled my young life. Nowadays I can't find anyone else to play in person ...