Settlers of Catan meets M.U.L.E. in Seize Life! describes a M.U.L.E.-inspired variant of Catan where players must co-operate and win together:

In M.U.L.E. the player are all in coopertition, cooperative competition. They are colonists trying to make good for themselves but also must help their fellow players. At a certain time “those in charge” return to see how the colonists are doing. If the players have been playing a cutthroat game they usually won’t have done well enough to be accepted as a successful new colony. They lose the game.

I applied this to Settlers. I kept track of several games and found that when playing competitively (4 players) the game usually ends around turn 15 with a combined point total of roughly 28.

We changed the rules. Now the game will end at the end of turn 15, and players must have reached a combined total of 35 points in order to win. If we don’t make it, we lose as a group.

Sounds pretty cool! Thanks to Yehuda for finding this.