I'm working on a game of fantastical alternate history that I'm calling The New World. It is essentially Guns, Germs, and Steel meets The Years of Rice and Salt: The Role-Playing Game, with a dash of Roger Zelazny's Game of Blood and Dust
The meta-game involves the accumulation of four types of civilizational currency (Warfare [i.e., offensive technology--think guns], Life [i.e., population and biodiversity--think germs], Wealth [i.e., luxuries and ostentation--think "cargo," in the WWII cargo cult sense), and Knowledge [in particular, technical and scientific knowledge--think steel]). Those currencies pay for scenes that produce fictional outcomes, which then feed back into the meta-game. So each session is like a chapter in a book of never-was history.
But to prompt the historical imaginations of the players, I want to begin the game with a little alternate history mini-game that will tie alternate history breakpoints or "points of departure" (PODs) to playing cards. Each player (who in the meta-game will represent one or more "zones" or "civilizational centers"--basically continents) will have a small hand of cards (probably 3 to 5) to play a trick-taking game that changes the initial distribution of civilizational currencies in line with the imaginable consequences of the POD associated with that card.
So, for example, I'm playing the mini-game, representing North America, and I've got the Queen of Hearts, which I know means that a comet misses the Earth in 10,900 BC, so there's no Younger Dryas ice age, so mammoths survive in North America, giving North America +1 Warfare (because they have war mammoths) and +1 Life (because domesticated mammoths are a biological resource and a source of pathogens). I lead with that card, and that event happens. If someone throws a card with a lower value, its historically more recent event doesn't happen (probably because of the butterfly effect), but if someone throws a card with a higher value, its historically earlier event does happen. So, for example, if the player to my left goes with the King of Diamonds (Atlantis really existed but sank in pre-historic times, so Atlantean refugees bring their super-science with them, giving +2 Knowledge to the zone of her choice), then she's winning the trick and will lead next, assuming no one plays an ace. But if she plays the Five of Clubs, then she's thrown away the opportunity to have Mohammed killed while fleeing Mecca. After three to five tricks, you've got (a) the starting date for the game, based on the lowest card that anyone led, (b) a world-historical sketch with hopefully evocative fictional elements: Vikings in America! Native American war mammoths! Chinese treasure fleets in the Atlantic Ocean! and (c) a starting distribution for the meta-game "civilizational currencies." I think it's fun and elegant in a Rube Goldbergian way.
So what I need are more points of departure! Give me your favorite alternate historical breakpoints and their imagined consequences! I think I want to stick to stuff that's prior to 1500, though, so no alternate Civil Wars or World War IIs or any of that Turtledove stuff.
Bill White's roleplaying game design blog, with emphasis on narrativist or story-heavy games.