These are games where the rules are intentionally concealed from new players, either because their discovery is part of the game itself, or because the game is a hoax and the rules do not exist. In fiction, the counterpart of the first category are games that supposedly do have a rule set, but that rule set is not disclosed.
- Bang Bang Who's Dead?: A game where most of the players don't know the rule. The director points randomly and says "bang" random amounts of times and then asks "who is dead?" The correct answer is whoever spoke first after the question was asked.
- Bartok: A game similar to Mao and Uno, and new players are not told the rules.
- Bobby's World (or My World): A game where players declare an item that is "in" their world, and those knowing the rule confirm or deny whether it is part of their world.
- Bugs: A game where the players must guess how many bugs are cupped in the leader's hands.
- Coffee But No Tea: Exactly like Green Glass Doors except for the characteristic of the secret rule. Typically, the first example is "In my world, I can have coffee, but no tea."
- Elephant's foot umbrella stand: A parlour game in which items are added to the end of a list. Only items which follow the rule are accept.
- Eleusis: A card game where the object of the game is to deduce, by studying which cards have been successfully played onto a layout, the rules by which subsequent placements may be made.
- The Green Glass Door: A word game that has a single rule that needs to be guessed by other players. Typically, players who know the rule will give a thematically matched pair of words, one of which "is" behind the green glass doors, and the other of which "is not."
- I Stole:A game in which players take turns in saying that the go to a supermarket and steal something. People in the know then say whether they have been caught, or have got away. According to some pre-decided rules. Also fun to pretend that rules exist and string other players along while they try to guess the rule.
- Jewels in the sand: A verbal version of Eleusis.
- Mao: A card game in which a new player must try to learn the rules by observations and it is taboo to spell out the rules.
- One Up, One Down: a drinking game with improvised jargon.
- Penultima: a chess variant in which the moves of the pieces vary, and are initially kept secret from the players.
- Petals Around the Rose: Is played with five dice. The unknowing part shall guess the number to be derived from the throw. It is also taboo to write the rules. It is also known by other names.
- Scissors: A game where a pair of scissors is passed, with the passer declaring that they are being passed "open" or "closed", and the players must figure out the rule determining which is the correct declaration.
- Stanley Random Chess: A computer moderated chess game where 50% of the moves are made randomly from a list of all possible legal moves in the current position. Players are told that their original moves were illegal and have been adjusted to the closest possible legal move.
- Take a plane: A game where players "take a plane" somewhere, and someone in the know says whether they get there or not.
- The Box Not In This Room: Exactly like Green Glass Doors and Coffee But No Tea except for the characteristic of the secret rule. Here, an item is either "in the box not in this room" or "in this room but not in a box."
- Umbrella: A game where players say a word and the players who know the game tell them if it is a correct word (see Take a plane).
- Zendo: A sculptural version of Eleusis.
- Mornington Crescent: Originally a round in the Radio 4 comedy panel game I'm Sorry I Haven't A Clue, Mornington Crescent involves naming stations on the London Underground, roads and streets until Mornington Crescent is "reached". The game parodies games such as contract bridge or chess.
- Progress Quest: A satire of MMORPGs, Progress Quest discussions will include gameplay tips, strategies, and hints, or give favorable reviews and boast of in-game accomplishments. However, the game is not interactive at all.
- Spoons: This game was featured in the movie Extreme Days but has since become quite popular in many youth groups. The victim is seated across a table from his opponent (who is, of course, in on the joke). The victim is told that the object of spoons is to hold a spoon in his mouth and hit his opponent as hard as he can on the head with it. He is also told that they will take turns and the first person to give up from the pain loses. Another person who is in on the joke stands behind the victim, apparently for moral support, but holds a spoon in their hand. When it is the victim's turn to be hit in the head, his opponent makes the motions as if he was using his mouth to hit the victim in the head with the spoon, but instead the person standing behind the victim hits the victim as hard as possible on the head with the spoon he is holding in his hand. The victim becomes slowly more bewildered as to why it hurts so badly when he is hit, but he is able to inflict little pain on his opponent. This continues until the victim figures it out.
- Tig Tag: A commentary on the extended version of The Lord of The Rings: The Fellowship of the Ring includes Elijah Wood, Billy Boyd, and Dominic Monaghan talking about an imaginary game called "tig tag". Apparently, Boyd and Monaghan were messing around, saying "tig" and "tag" randomly, when Wood walked up and asked them what they were doing - whereupon they quickly invented a whole set of fake rules, like "No! you can't put a double tag before a tig!" It seems Wood thought the game was genuine, and a few years later asked the others why they didn't play it anymore.
- Derby: a card game in which players draw and discard cards based on whatever seemingly-logical rules each individual player may choose, until one player calls "Derby!" and is declared the winner by the dealer, at his discretion. The dealer generally wins.
- Genghis: A parody of games such as "Mao", this game proceeds like in crazy eights, with apparently complicated rules being followed with each discard. Usually one or two players are unfamiliar with the game, but are familiar with Mao, and are tasked with figuring it out. The players in the know amuse themselves by penalizing each other and acting silly, while the players left out struggle to understand why they are being penalized each turn. Red Herrings are sometimes thrown into the mix, such as the player to the left of a Canadian singing O Canada on their turn.
Games in works of fiction
Games with undisclosed rules
- The Glass Bead Game: Hermann Hesse's eponymous novel includes this game. To properly play requires synthesizing all societal knowledge.
- Bao: In Wilbur Smith's books River God Warlock and The Seventh Scroll, an ancient form of Chess called Bao is played frequently, however the full rules are not disclosed, although this situation may be changed by his new book The Quest (confirmation needed). This game should not be confused with the East African board game of the same name.
- Brockian Ultra-Cricket: In Douglas Adams's The Hitchhiker's Guide to the Galaxy is "a curious game which involved suddenly hitting people for no readily apparent reason and then running away"
- Calvinball: In the Calvin and Hobbes comic, Calvinball is an improvised sport played by the two main characters, where the only rule is that rules can't be the same twice.
- Cripple Mr Onion: This game is referred to in various books in Terry Pratchett's Discworld series. It is a card game whose rules are never directly specified, but are very complex.
- Double Fanucci: Featured in the computer game Zork Zero, Double Fanucci has mind-bogglingly complex "rules". Legal play can depend on things like the phase of the Moon and the ancestry of the players.
- Go Johnny Go Go Go Go: This fictional card game is featured in episode 3, series 2 of The League Of Gentlemen.
- Guyball: A sport played in the British sitcom Green Wing, Guyball is a very complex game where each player wears a basket on top of a helmet, while other players attempt to throw balls into it.
- House Rules Parcheesi: The characters in DC Simpson's online comic Ozy and Millie play "House Rules Parcheesi", which always ends with the house strewn with tennis rackets, socks, couch cushions stacked in complicated positions, etc.
- "I Ruff, I Huff": The Tom Stoppard play The Real Inspector Hound has several scenes where people in a seaside mansion are playing a card game that has commentaries such as "I Ruff" and "I Huff", and follows no obvious known card game's rules. The objective seems to be that the 'odd person out' in the scene loses.
- Numberwang: A sketch, created for the radio series That Mitchell and Webb Sound, where players call numbers until the host declares, "That's Numberwang!"
- Xing Haishi Bu Xing: In the episode "Atlantic City" of How I Met Your Mother, Barney plays a game entirely in Chinese. Marshall, however, figures out how to play the game, giving Barney clues as to how to play. Barney wins by going all in, spinning a roulette wheel, and choosing the girl who is holding the Jelly Bean. He shows this victory by declaring "Ning Na".
- In Fairly OddParents, Timmy invents a game called 'Timmyball', in which Timmy makes up the rules and changes them as he pleases, and Timmy always wins - breaking the 'Timmy always wins' rule is not possible. This is very much like Calvinball, as made famous by Calvin and Hobbes by Bill Watterson.
- In Star Control II, certain members of the Zoq-Fot-Pik race are fans of the sport 'Frungy'. The only detail about the sport disclosed to the player is that Frungy is played "with gusto".
- Several invented games feature in Star Trek episodes. For instance, throughout The Next Generation, repeated references are made to Parrises Squares, a game which is never explained but is apparently quite dangerous.
- On Firefly, Simon, Jayne, and Shepard Book are seen playing an unidentified card game. The cards are round, and at least one is a picture of a plum. The rules of the game are never made clear.
- In Fallout 2 the player is able to play a game called 'Tragic: The Garnering', and obvious parody of the card game 'Magic: The Gathering' that uses ridiculous rules that alter gameplay such as the day, and position to dealer.
- Chinaman's Whist: Featured in the Hancock's Half Hour episode, The Tycoon, the fictional card game is invented by Sid James to fleece Hancock and his rival, Aristotle Thermopylae, of their great wealth. Additional rules are revealed by Sid after each round to give him the winning hand.
- Clique: The online satirical gaming magazine Critical Miss featured rules for a card game called Clique, a parody of collectible card games that used printed cards and spurious spoken rules to confuse onlookers.
- Double Cranko, Triple Cranko: The episode of M*A*S*H "Your Hit Parade" (1978) featured Hawkeye Pierce and B. J. Hunnicutt playing an incomprehensible game called "Double Cranko", and alluded to the presumably more complex "Triple Cranko".
- Creebage: In one episode of the television series The Monkees, the character of Micky Dolenz invents a card game on the fly with incomprehensible rules known as Creebage, to distract an old-style gangster holding him captive. While the gangster is distracted, Micky escapes, with the gangster holding up some cards and shouting, "But, I have a creebage!"
- Cups: An episode of Friends featured a card game called Cups, which one character (Chandler) had devised as a method of giving money to another character (Joey) without Joey realizing it. Thus, Chandler made up rules on the fly so that he would always lose. (Unfortunately, Joey then played the game with another character, and lost all the money he had won.)
- Fizzbin: In the 1968 Star Trek episode "A Piece of the Action", Captain Kirk spontaneously invents a card game called fizzbin after being captured, in order to distract the henchmen guarding him.
- Go Johnny Go Go Go Go: The British sitcom The League of Gentlemen features a card game indirectly inspired by Mornington Crescent called Go Johnny Go Go Go Go which has rules which appear to be entirely fictional (or deliberately overcomplex and obfuscated) for the purposes of defrauding naive players.
- Jiggly ball: In episode My Jiggly Ball of Scrubs, Janitor tricks the main character J.D. into accepting that he knows how to play the nonexistent game jiggly ball. Janitor then challenged J.D. to a game in which many hospital staff members pelted him with tennis balls. J.D. then realized there was no actual game called jiggly ball but his pride prevented him from conceding to Janitor earlier.
- Spat: This card game could be seen as a precursor to Mornington Crescent. It was played in the episode of The Goodies entitled 'Holidays' (from the LWT series). Tim and Graeme knew all sorts of "secret rules" while Bill had never played before and consequently lost every round.
- TEGWAR: The book Bang the Drum Slowly by Mark Harris includes a game called TEGWAR, The Exciting Game Without Any Rules. Played by professional baseball players as a way to dupe unsuspecting fans out of their money, the game features rules that are made up on the spot. Each time a non-initiate thinks he's understood how to play, he's told of a new wrinkle in the rules that he somehow didn't catch. (The game also appears in the 1973 film of the same name.)
- Dragon Poker: A fictional card game by Robert Asprin in the MythAdventures series. The rules change depending on weather, seating position, time of day, and undisclosed other modifiers.