The premise of the game is that the Protagonists are people who, for various reasons, have been unable to sleep for a long time, and they begin to see the extra doors and windows that lead to the Mad City. The Mad City is a strange, twisted place where Nightmares walk in the ever present night and lost things end up. The Protagonists must deal with these Nightmares, most of whom would love to taste their Awakened flesh and souls, to complete their personal journeys.
While often compared to an extremely creepy Alice in Wonderland, the specifics of the game, particularly some of its Nightmares, are probably closer to a deranged version of The Phantom Tollbooth. The author himself notes strong influences from and similarities to Neverwhere and Dark City.
The game heavily emphasizes role playing over mechanics, encouraging to roll only for conflicts and to settle them in a single roll when possible. This is largely because almost any roll has a chance of influencing the Protagonist's few stats and leading to self destruction.
The game mechanics use a dice pool system that incorporates three different colored dice for the protagonists to represent their three stats: Discipline, Madness and Exhaustion. The Game Master uses only a single color of dice for the only stat of all Nightmares and obstacles: Pain. Any dice rolled three or under counts as a success, which are added up, but whichever color comes up highest dominates the scene, creating separate effects (which are almost always bad) depending on which color is dominant. The two effects are separate and have separate effects, almost always bad. This leads to Protagonists slowly wearing themselves down to the point of death, collapse (a Fate Worse than Death), or becoming a Nightmare (a fate even worse) even as they become more powerful.
Protagonists also have two special abilities: Exhaustion abilities, which describe some mundane action they can do exceptionally well and Madness abilities, which let them do something literally impossible.
Protagonists are encouraged to take narrative control over how they succeed and what they do.
As of yet one supplement to the game exists: Don't Lose Your Mind, which describes in more depth how to use Madness powers and a great deal of examples to use. It also has some suggestions and alternate rules to crank it Up to Eleven.
This role-playing game provides examples of:
- Alien Abduction: The Xenophile power from Don't Lose Your Mind causes these to happen to you.
- Beneath the Earth: Underneath the Mad City is a system of caves, caverns, and twisting tunnels known as the Warrens. While many known and unknown things live down below, the Warrens are most famous for the Kingdom of Wax, the domain of the Wax King.
- Bad Cop/Incompetent Cop: Say hello to Officer Tock and his Clockwork Cops. The Cops are weak and ineffective. Tock on the other hand...
- Boarding School of Horrors: Mother When runs one of these. It's also the only school in the Mad City.
- Body Horror:
- Fill up your Madness quota, and *whoosh* — you're a Nightmare. They are invariably extremely bizarre fusions of Victorian citizenry and the art of Salvador Dali. It doesn't help that they're suffering as much as everyone else.
- This can happen even before becoming a Nightmare with some of the freakier Madness talents in Don't Lose Your Mind. Who wants the ability to open up their ribcage and imprison people inside of it?
- Bazaar of the Bizarre: Welcome to the Bizarre Bazaar, where dreams and memories, as well as other oddities can be exchanged for goods and services! Strangely, while those at the Bazaar tend to be at truce, the gathering is illegal. It only occurs at 13 o'clock, when the Mad City is at its most deadly, and can be considered one of the "safer" places to be at the time.
- Brought Down to Normal: If you survive falling asleep despite having turned into a Nightmare magnet, you're Brought Down to Normal when you wake up. And still a Nightmare magnet until you regain your powers. Have fun. The rulebook actually suggests you might want to have your character Killed Off for Real instead of falling asleep when they crash, because it's not as bad.
- Cast from Hit Points: An Awake can boost is Exhaustion talent if he takes one Exhaustion point, which equals as sacrificing some health.
- Cluster F-Bomb: One of the sample Madness Talents described in the Don't Lose Your Mind supplement is a weaponized form of this. Whenever you say fuck, it intensifies things (If you say that there is a fucking fast car it could outspeed a racecar, if a dude is fucking huge he becomes a giant, etc.). Overuse of this power turns you into a perpetually swearing Nightmare known as a Fuckwit.
- Critical Status Buff: Two versions:
- Exhaustion: if a player gets tired, they gets a minimal amount of successes when he acts on his Exhaustion talent. Also, voluntarily increasing your Exhaustion score to boost said talent gives you a bonus proportional to your new level of Exhaustion.
- Madness: as a player goes insane, its Discipline gets converted into Permanent Madness, which don't count for the "6 Madness dice" limit. Since the amount of Madness required is proportional to the effect you want, Permanent Madness can push your talent to great heights.
- Dark Fantasy: Of the non-standard variety.
- Dark World: The Mad City, which is usually the entire setting of a campaign.
- Demonic Dummy: Overuse the Ventriloquist power from Don't Lose Your Mind, and the dummy into which you've been projecting your consciousness will kill you and go on to become a Nightmare.
- Does Not Know His Own Strength: One of the possible results when Madness talents fail: they do what you asked from them and more, but the excessive results make you fail your immediate objective or hurt you in the process.
- The Dreaded: Don't Lose Your Mind notes that if you've recovered from Permanent Madness, many Nightmares will be terrified by you. It means you have seen the abyss and come back whole, which is exactly what they failed and why they become Nightmares.
- Earn Your Happy Ending: It is possible for one of the Awake to defeat their inner demons and external foes, accomplish their goals, and return to City Slumbering without the constant threat of death or worse than the Awake always face. Possible and easy are not the same thing, however — and the Mad City is full of people that failed or gave up. Worse, it's Bittersweet Ending at best. Once ones become the Awake, they will find the City Slumbering has become dulled and as strange as Mad City was, it's hard to enjoy their normal life afterward.
- Emergency Taxi: An anywhere-anytime taxi is one of the Madness Powers a character can develop. There's just always a cabbie nearby who will take you anywhere, getting you out of harm's way for a bizarre, arbitrary, and more often than not abstract fare.
- Empty Shell: The human civilians of the Mad City. If one of them is an accountant, then he is an accountant all the time, and nothing else.
- Exactly What It Says on the Tin:
- Extreme Omnivore: One of the perks of the Innards power from Don't Lose Your Mind is that you can live on anything small enough to swallow, regardless of how harmful it would be to anyone else.
- For the Lulz: If Tacks Man hunts you down by himself, then he's in it for pleasure, not business.
- Gone Horribly Right: The dice rolling system can result in this sometimes. For instance, if the player's dice pools gets the highest amount of successes (getting 1-3 in a D6 dice), but the GM's dice pool (the Pain pool) gets the highest numbers overall, it means that the player's character is able to do what he intended, but it will not be efficient as he thought or it will have some bad and unexpected consequences.
- The Grim Reaper: Mother When is believed to be an incarnation of Death, released into the Mad City the one and only time that someone managed to open one of the doors during the 13th hour.
- Hearing Voices: The Ears talent from Don't Lose Your Mind has you being advised by a group of often creepy voices which only you can hear.
- The Heartless: Nightmares tend to embody the worst aspects of humanity — hatred, sleazy journalism, police brutality and incompetence, heartless psychology, gluttony and greed, etc.
- The Hidden Hour: The Thirteenth Hour, which exists only in the Mad City. For those in the City Slumbering, it seems that the Mad City has gone forward by an hour. For those in the Mad City, it has been an hour where they couldn't escape back to reality and every Nightmare takes advantage of this. Somebody actually managed to pry a door open during this period. That's when Mother When entered the Mad City.
- Humanoid Abomination: Almost all the Nightmares are human-like, except for some characteristics that give the impression that they all came from a surrealistic painting.
- Hurricane of Puns: Every single Nightmare, and some things besides. Go ahead and laugh if you think the names are funny, because their description will wipe away that smile from your face.
- Intangible Theft: The Tacks Man attacks his victims and steals intangible concepts from them, like their names or their heartbeats, then later adds those "stolen goods" to his private collection.
- Inverse Ninja Law: Another sample Madness Talent described in Don't Lose Your Mind plays with this. You can summon a legion of ninjas to do your bidding, but being a legion of ninjas, they are all Made of Plasticine — their usefulness is mainly in their ability to Zerg Rush anything. Playing the trope a bit straighter, you can instead summon a single, highly competent ninja specializing in anything from explosives to dancing.
- Killer Game Master: Encouraged or even required, as every Despair coin the GM uses to fuck you over will turn into Hope coin, which can be used to turn things into the players' favor, most vital of which is regaining Discipline.
- Mind Control: The Yes power from Don't Lose Your Mind means that you can make people say yes to you and mean it.
- Never Sleep Again: The player characters. It's even on the title.
- Noble Demon: The Wax King may be trying to drown the city in wax, but he is very nice compared to the other faction leaders. This is to the point that there's some debate over whether he's actually a Nightmare at all — some suggest his similarities to a Nightmare are superficial and he's actually one of the Awake. A remarkably old and powerful example, and a bit changed by his time in the Mad City, but certainly not a Nightmare.
- Non-Human Head: Some Nightmares, such as Officer Tock and the Tacks Man, have this characteristic.
- One-Man Army: Any one of the Awake can easily bring a terrifying amount of destruction to the table with their Madness Talent. Even a failed roll can have game-changing results. Furthermore, a fully maxed-out (and possibly suicidal) Awakened brings 15 dice to the table: this is enough to overpower the strongest Nightmares described in the book by a fair margin. Of course, bringing all 15 dice to the table is just as bad for the player as for any enemy...
- One-Winged Angel: Officer Tock is normally a medium-high difficulty opponent. Normally, because he has three situational modifiers that increase the difficulty of facing him — having a warrant against the players (the manual suggests it can be obtained either by making the player themselves sign it in exchange for some favour, or by the player making a real mess in Mad City); being in the 13th District; and the 13th hour activating. If all three modifiers are active simultaneously, Tock is tied with Mother When as the most powerful Nightmare in Mad City.
- Power Born of Madness: Madness Talents come from this.
- Punny Name: Seem to be standard for the Nightmares. Examples including Officer Tock, Tacks Man, Ladies in Hating, Paper Boys, Agony Ant, Handyman, and so on. They're Exactly What It Says on the Tin mixed with Black Comedy.
- Reality Warper:
- Madness Talents can take this form, such as a sample one that lets you alter reality by speaking the language God used to create the universe. The Nightmare for this one is a mindless disembodied voice that warps and perverts things by describing them, known as the Omnipotent Third Person.
- To a degree, any Madness Power is an example of this, even ones that don't obviously seem like it, since they work on dream logic. Someone with Super Strength can lift cars, smash concrete, and bend steel bars like anyone else with such powers, sure... but they can probably also lift someone's spirits, smash injustice, and bend the truth. And yes, this will likely involve their muscles straining and veins bulging while they cheer someone up or spin a convincing half-truth.
- Anything the Paper Boys publish in their paper comes true. This is a very bad thing if they decide to publish a story about your death (the Pain rating for avoiding it is only two points down from Mother When). However, if the story is prevented from circulating, it has no effect. The Wax King spends most of his time shutting down branches of the Paper Boys that are trying to kill him this way.
- Sinister Subway: The Underground power from Don't Lose Your Mind lets you visit some very peculiar subway stations.
- Shock and Awe: The Zap sample power from Don't Lose Your Mind.
- The Sleepless: The player characters, by definition.
- Sociopathic Hero: The player characters can swing this way.
- Superpowered Evil Side: Getting carried away with their Madness talents will cause a person to transform into a terrifying Nightmare. Unlike most instances of this trope, the transformation is not reversible.
- Surreal Horror: The whole setting, from the nature of the Mad City and the Nightmares and even to the powers of the protagonists themselves.
- 13 Is Unlucky: Every 12 hours, there is a 13th hour. Where you cannot escape from Mad City. And every Nightmare is out for hunting. Good luck. Two Dark Hours a day? Oh, Crap!
- There is also District 13.
- To Hell and Back: The whole point of the Orpheus power from Don't Lose Your Mind.
- Voodoo Doll: The Teddy sample power from Don't Lose Your Mind is a variation on this. If the user damages the teddy bear, the environment takes a proportional effect. Shake it, and a small earthquake happens; set it on fire, and an city block explodes.
- Was Once a Man: Many Nightmares and denizens of the city.
- Weirdness Censor: Anything related to the Mad City has this effect on normal people. If someone enters the Mad City through one of its many strange doors in full view of a normal person, that person will remember them leaving by some other mundane means. When an entire district was pulled into the city, everyone remembered the district being destroyed by a freak fire. It's implied to be an actual defense against the Nightmare, making it an Achievement in Ignorance. Just not foolproof.
- With Great Power Comes Great Insanity: Possibly the other way around. The more the Awake use their Madness talents, the more they risk falling deeper into madness. Whether their power comes from madness, or their madness comes from power, using their power definitely makes the madness worse.
- You Cannot Kill An Idea: Oh you definitely can, when you are using the Knife Madness Talent, as the knife can kill anything. There's a ritualistic quality to the deed, dubbed memeticide, but once it's done (for example, slashing Fidel Castro's throat to kill Communism in Cuba), the idea stops being credible, loses all political momentum, and will become a joke of an idea that will never be taken seriously anymore. That being said, the knife can also cut off flaws, sever unhealthy relationships, and kill personal demons.
- Zerg Rush: The higher-end application of the Ninja power. They're laughably weak individually, but there's strength in numbers, and the sourcebook itself puts it best: 'Call forth so many ninja that even Zatoichi would have trouble.'