Yesterday I had an idea for a game. It started as an "Apolcalypse World" hack, but developed into a different game.
The main theme is kinda similar to that of AW: your world has been f**ked up by something (someone, in this case), and you have to cope with it.
Think of many fables and child books with talking/sentient animals and other similar creatures: the "Redwall" series, fables, the works of Beatrix Potter, "Watership Down" and the like. Imagine they all reside on the very same place/continent/planet/what-you-have, in the Realm of Fables. All the inhabiting creatures lived a quiet, simple and enjoyable life... until the evil witch-queen of the Fairy World, before being defeated by the local hero-prince, manages to cast a powerful spell that also impacts the Realm of Fables, bringing a real armageddon over there.
Most of the inhabitants survive, luckily, but their world is no more so quiet and enjoyable: trees think, speak and move, and some of them even started liking flesh; the earth shakes more than what should be considered normal, and sometimes vile things come up from the bottomless pits that pop up here and there; many non-sentient animals start behaving in weird ways, often against their usual habits; magic is now almost a living creature, with a will and sometimes even a body.
Now, they have to face all of this and maybe try to bring back some hope and trace of the old civilization, in order to survive.
Speaking of the system, it stems from "Apocalypse World," as I said. Players gather around each session, using the first one to decide what happened and choosing the things they'd like to see in the upcoming sessions. They get to decide which creatures they'd like to play, for example, how weird their world has become and what changed. Each species has a list of interesting features and players will have to choose which ones have changed and how. Then, they choose a playbook and a species for their character. Playbooks, this time, come out from the classical heroic fantasy repertoire: the Mage, the Warrior, the Noble, the Wanderer and the Mystic. Each playbook has general-use moves and special moves for single species. This time, when you choose a playbook you have to acknowledge that there will surely be another character in the world who mirrors you in almost everything, and you'll surely have to confront him/her sometime.
Then the MC starts describing things and moving NPCs. NPCs are divided in henchmen and real people, who also have shortened playbooks to ease the role of the MC. I still have to decide for Characteristics, harm levels and so on, but more or less this is the game.