History Main / UniquenessRule

* ''[[TabletopGame/TheQuacksOfQuedlinburg The Quacks of Quedlinburg]]'': The titual witches in the ''Herb Witches'' ExpansionPack give players access to a once-per-game power.

*** Also in 5e, in a related idea, while there's nothing preventing there from being more than one of the same AOE spell on the battlefield at the same time, if the copies overlap, a creature will only be affected by one copy (make one saving throw, take damage once,
etc.), not both.

** ''TabletopGame/DungeonsAndDragonsFifthEdition'': In order to limit the power of player characters compared to previous editions, 5e characters can only be attuned (linked to; a character can only attune to three magic items at a time) to one copy of a magical item to prevent things like attuning to three copies of the best ones that the character can afford in order to stack their benefits.

** Castling is a special move that moves both your king and a rook, and is only available if neither of the involved pieces has ever been moved. This means that it's only usable once per game and can't be repeated even if the king and rook somehow return to their original positions.

** "[[https://hearthstone.fandom.com/wiki/Highlander Highlander]]" cards have extremely powerful effects but have the restriction where your deck cannot contain any duplicates when they're played. Normally this restricts them to a no-duplicate deck. However, you can play a deck that expects to draw all of its cards very quickly, letting you activate the cards after all of your duplicates have been drawn.

* In the ''{{Anime/Pokemon}}'' anime, battle gimmicks are limited to once per battle much like their appearances in the video games. In addition, in the World Coronation Series arc of the ''Anime/PokemonJourneys'' anime, all competitors are limited to just one gimmick and only once per battle so Trainers who don't have Mega Evolution, Z-Moves or Dynamax can still compete on fair terms with those that do. [[spoiler:This rule is only lifted for the final fight of the Masters Eight Tournament, where Leon asks for an exception so that Ash can use all three against him. Eternatus also appears during the final battle to give both competitors a second Dynamax.]]

* [[TabletopGame/TheQuacksOfQuedlinburg The Quacks of Quedlinburg]]: The titual witches in the ''Herb Witches'' ExpansionPack give players access to a once-per-game power.

** In the Commander format, originally known as "Elder Dragon Highlander," each card in your deck has to be unique. The only exceptions are basic lands and cards with the very rare effect of explicitly allow you to go above the normal limit. (Hence the "Highlander" part: To quote the TagLine, "[[Series/{{Highlander}} There can be only one]].") Moreover, you can only have one commander (all of which were originally the five Elder Dragons) unless the cards explicitly say otherwise.

* Downplayed in ''VideoGame/SlayTheSpire''. While you can pick up as many copies of a card as you want (assuming you can find them), your score gets the Film/{{Highlander}} bonus if your deck contains no duplicates.

* In ''TabletopGame/{{Everdell}}'', your village can only contain one copy of critters and constructions with the "unique" property. This somtimes has a thematic justification (it makes sense that you can only have one King or Queen), but more often than not it just serves to keep you from spamming cards that would be too good in multiples.

* In ''TabletopGame/{{Everdell}}'', your village can only contain one copy of critters and constructions with the "unique" property.

* ''VideoGame/YuGiOhDuelLinks'' has a much harsher Limited list compared to the regular game, as you can only play 1 Limited card in your deck, period. This means you can't play multiple Limited cards at the same time.

* ''TabletopGame/IlluminatiNewWorldOrder'' being a world domination game, only allowed one copy of any location or person to be in play at one time. After all, you can't have two different secret societies controlling the Pentagon at once!

* In ''TabletopGame/{{Warhammer}}'' and ''TabletopGame/Warhammer40000'', you are generally only allowed to field one of each named character in a game.

* ''TabletopGame/{{Chaotic}}'': Certain cards are classed as "Unique" meaning only one copy of a card with its name is allowed in a deck. This rule extends to cards with different versions (I.e. Maxxor and Maxxor: Protector of Perim) as well.

** There are moves that remove a user's typing on use, such as Roost, Burn Up, and Double Shock, and once the user loses their typing they can no longer use that move again until they switch out or the battle ends. However, in ''Scarlet'' and ''Violet'', Terastalizing can be used to get around this since Tera Types can't be removed, enabling multiple uses of these moves in a row.