In the post-apocalyptic world of Leftovers, there are two primary forms of life: humans and Horrors. And it's not always easy to tell them apart.
Not many humans are left -- no one knows how many, and there's no good way to find out. The Elder Horrors, the monstrously huge things that slithered across the world, devoured most of Mankind, but a portion escaped their notice, usually because they weren't worth noticing. These are the player characters. Despite how few humans are left, the scarcity of resources, harsh living conditions, and ever-present Horrors haven't done wonders for their sense of unity. There are gangs and factions, authorities and criminals, killers and thieves. Some fight to keep the insanity at bay, and some go insane right along with it.
The Horrors are creatures undreamed of by Man except during the deepest throes of madness. Or something. There seems to be a near-infinite variety of the things, but all of them are terrifying creatures of death and destruction. They stayed behind to claim the table scraps of humanity after the Elder Horrors moved on.
Leftovers doesn't take place anywhere in particular, but wherever you choose to set your game there are a few geographic features in common. First, there's the Trench, a miles-long cleft riven in the Earth during the conflict that's become home to the closest thing to civilization anyone knows. The Trench Authority provides law, order, and security, but rules with an iron fist. Still, an iron fist is better than a tentacle, right? Outside the Trench are the ruined remains of a nearby city (the Ruins) and the blasted-out, dried-up Wasteland as far as the eye can see. Somewhere out there, so the rumors go, there's the Bunker, an ultra-secure post-apocalyptic Utopia with electricity, running water, plenty of food and guns, and a total absence of Horrors.
Characters are defined primarily by their Natures and Traits.
There are two Natures: Human and Horrific. The more Human you are, the less Horrific you are, and vice-versa. Everybody’s at least a little bit Horrific, but the Horrors are completely in-Human. Humans can completely lose their Human Nature, too, if they sink low enough.
There are 18 Traits, so we’re not going to list them all here. Traits represent skills, affinities, professions, interests, and so on. A character might be good at fighting, or scientifically minded, or sneaky, or whatever. When you want to do something, you’ll be using a Trait.
There are three other elements of a character that, unlike Natures and Traits, are situational, in that you won’t always be including them for every roll of the dice. These are Bonds, Tools, and Grafts.
Bonds are a character’s emotional ties to other people – specifically, they’re ties to other characters. These come in four basic varieties: trust, distrust, loyalty, and betrayal. The higher your Human Nature, the stronger your Bonds. As your Human Nature slips, so do your connections to other people.
Tools are items that help characters accomplish tasks, from a set of lockpicks to a length of rope to a socket wrench to a .38 Special. Usually, a Tool can only be used with a specific Trait. The higher your Human Nature, the more Tools you can own. As your Human Nature slips, so does your attachment to worldly possessions.
Grafts are body parts from Horrors that have been transplanted onto a character’s body. These come in three varieties: Greater, Lesser, and Minor. Greater Grafts are things like giant bat wings, or two writhing tentacles in place of a character’s arms. Lesser Grafts are less severe, such as a tail or a single replaced limb, and Minor Grafts are much smaller: a Horrific (or third) eye, a claw hand, or a sharp-toothed mouth in a surprising new location. They also make people tougher and more survivable -- big pluses in the post-apocalyptic landscape -- and confer amazing recuperative powers when first transplanted. Many a life has been saved, or at least prolonged, by the timely application of a Graft.
Each of these five components is rated in die size, usually from d4 to d12. We’ll refer to these as your Trait die, your Nature die, your Bond die, and so on. Whenever you want to do something that requires a roll, you’ll roll one Trait die and one Nature die, add the results together to get your total, and compare that with a target number, or Target, to see if you succeeded or failed. If a Bond, Tool, or Graft is relevant, you’ll roll one or more of those, too.
For example, if you’re trying to fix a car and you have an ace set of tools, you’ll roll your Mechanical die, your Human die, and your Tool die. If you’re trying to steal Jim’s car and your Bond with Jim is “I’d betray Jim for a nice set of wheels,” you’d roll Mechanical, Human Nature, and your Bond with Jim.
Sometimes the rules refer to steps with regard to dice, like "+2 steps" or "-1 step." Sometimes, a move up to the next highest die is called a "step forward"; a move down to the next lowest die, a "step back." For example, if you’re rolling a d6, +1 step would mean rolling a d8 instead; +2 steps (or "two steps forward") would bump that d6 up to a d10, and -1 step (or "one step back") would make it a d4. Dice can’t be raised higher than d12 or lower than d4, unless stated otherwise.
Those are the basics of the game.