"Backgammon's the oldest game in the world. Archaologists found sets when they excavated the ruins of ancient Mesopotamia. 5,000 years old. That's older than Jesus Christ."
"Two players. Two sides. One light. One dark."
That scene in the first season bascially sums up the sixth. Think about it...with all this talk of rules and the constant light and dark imagery...The final season is a game of backgammon.
No, I don't actually think that these guys are literally using this island as a board to play the most epic game of backgammon ever (I have always thought, however, that the 18th episode of this season should actually be a joke finale, where they did something like that or they were about to give us the last answer when they just zoomed out of a snow globe or a close up of vincents eye or something, and then the fans would be like "oh no you didn't" and then they played the real finale the week after), but it is very similar to backgammon. There are these two opposing forces, and then there are all the people in between, which would be like the pieces, who are being "claimed" and captured and told who is good and who is bad. I suppose, if it were necessary, any game would have the rule "you can't kill your opponent", which is why MiB had to find his loophole
But my point is, on a serious note, that if you have two opposing sides and you have rules, then what you're basically doing is a game. I think this particular game is very serious and it's not being played for the sake of fun or enjoyment, but I think that this season, excluding anything to do with timeleines, will very soon do two things: 1. Begin dividing the "pieces" into light and dark, and 2. Establish the incentive to win. I also think that in order for it to continue, Jacob's replacement must emerge.
It might not play out as literally as that, but I think it's undeniable that, based on that one scene, this season will in some capacity mirror a game of backgammon.