Current project (as a break from Magicians of England, naturally):
Darkening is a true epic level RPG, where players take the role of factions or races and play out their fate across a very large canvas. Characters in this setting don't have sheets, they are elements on a larger sheet.
Players start out by collaboratively creating their universe. I'm thinking specifically science fiction settings, but this needn't be the case. They answer a series of questions to determine the scale of the setting, the existing political and cultural order, history, and so on.
During this phase, they determine (in the most general terms) the nature of "the Threat". Depending on the nature of the threat, certain rules and mechanics may or may not be in play, or may be modified. For example, if "insidious rise of the darkness" is an aspect of the threat, the game includes a "darkness" dice pool that can be called upon at any time, but with certain implications for the player who calls it.
Next, players create their own factions. These could be anything from noble houses, to religious orders, cults, or entire alien races. Races have agendas which they can change during play, but not too often. Your agenda is a way of giving other players permission to change things in your faction, while keeping other things for yourself. For example, if you choose the "against the odds" agenda, faction characters can't be killed without your permission (they always prevail against the odds), but it also limits your ability to grow and gain power through conflicts. If you choose "transformation through destruction", then your faction members may be killed, but when they do, you get a bunch of points you can use to transform your faction. An example: your homeworld is overrun by the Threat, so your race is transformed into a race of restless wanderers doomed to journey from star to star.
Faction members include characters, but can also include places, things, and maybe even ideas or philosophies.
Factions also have an assortment of in-game goals of different scales ranging from proximate (something I want to achieve in this session) to cosmic (an ultimate goal that I will never reach in the course of play, but that I get points for pursuing). An example of a proximate goal might be the capture of a strategic planet. A cosmic goal might be transcendence of the physical realm, or mastery of the galaxy.
Players must balance antagonism between one another's faction against the impending threat. When players antagonize one another, it is to their mutual benefit. For example, let's say my faction and yours are at war. I decide I have a master spy among your people. To get free points to build my spy, I decide he has a nemesis, an admiral in your fleet. You get an admiral in exchange for my spy. Later, when our forces clash, the conflict creates more points that can be used to transform, change, grow, or otherwise embellish ones faction or maybe to take a shot at the Threat itself.
The Threat itself develops in play, starting as a vague list of aspects, and becoming more pronounced (and more powerful) in play. For example, I decide that the Threat's source is in the Black Nebula. I write this on the Threat's sheet. This gives me points to create an exploration fleet to go poke around in the Black Nebula and cause trouble.
Play proceeds by the players attempting to manipulate the universe through the agency of their faction members and to antagonize other players either by using their own faction, non-aligned entities, or the Threat. Naturally this 'antagonism' is to everyone's advantage and is the only way to get enough points to define and ultimately defeat the Threat. Or maybe they don't.
I have an idea this could be gamemasterless, but I'm holding that decision back until I see how it plays out.