Duel Monmusus

Duel Monmusus is a card game played in the Monster Musume franchise that has its origins in ancient Egyptian culture.

History
Some 3000 years ago, a "barbarous blood sport" was used to decide matters of grievance in the culture of the Mummies until Duel Monmusus was invented as a more "civilised" alternative in settling disputes. Up until recently, the inventors and stewards of the game such as the Letopolis family entrusted the continued development of the game within modern human culture to an unnamed human card company, presumably keeping the truth of their origins a secret. But following the Interspecies Exchange allowing them to reveal the existence of extra species in the world, the stewards publicly revealed themselves and sought the aid of Black Lily Advanced Materials Laboratory to increase their business ventures in regards to the card game.

Gameplay
Players draw cards from their respective decks and take turns playing cards onto "the field". Each player uses a deck containing forty to sixty cards, and an optional "extra deck" of up to fifteen cards. Each player starts with 4,000 "life points" (LP) (Though the players can decide to start with more or less), with the main aim of the game to use monster attacks and spells to reduce the opponent's life points. The game ends upon reaching one of the following conditions:
 * A player loses if their life points reaches zero. If both players reach zero life points at the same time, the game ends in a draw.
 * A player loses if they are required to draw a card, but has no more cards to draw in the main deck.
 * Certain cards have special conditions which trigger an automatic win or loss when its conditions are met.
 * A player can forfeit at any time.

There are at least two known game styles: the original, around 3,000 year old "classic style" and the "modern style", which only emerged in modern times. The difference between these two game styles is that in classic style there are no costs to summon a monster, which means that both players can summon any monster they want at any time, even allowing to summon a powerful level 8 monster on the first turn.

Field Zones
Cards are laid out in "the field" in the following manner: Main deck: The player's main deck is placed here face-down, and can consist of 40 to 60 cards. Normal, Effect, Ritual, and Pendulum Monsters can be stored here. Spell and Trap cards are also stored here. Extra Deck: The player's extra deck is placed here face-down, if they have one, and may have 15 cards consisting of Fusion, Synchro, XYZ, and Link Monster cards. Pendulum Monsters are placed face-up here when they would otherwise be sent from the field to the Graveyard. Graveyard (GY): A zone where cards are sent when they are discarded or destroyed, such as used Spell/Trap cards which were used or Monsters that are tributed or destroyed in battle. Main monster zones: A field of five spaces where Monster cards are placed when successfully Summoned. Link monsters and Pendulum monsters can only be summoned to the extra monster zone, or a main monster zone a Link monster points to. Extra monster zones: This is a zone where monsters from the extra deck can be Summoned. Spell/trap zones: Five spaces in which either Spell or Trap cards can be placed. The leftmost and rightmost spell/trap zones can optionally be treated as "pendulum zones" by placing pendulum monsters there, allowing players to use pendulum effects and perform pendulum summons. Field zone: A zone where Field Spell cards are placed.
 * Cards that are "banished" by card effects are placed outside of the game in a pile.

Phases
Each player's turn contains six phases that take place in the following order:

Draw phase: The player draws one card from their deck. Standby phase: No specific action occurs, but it exists for card effects and maintenance costs that activate or resolve during this specific phase. Main phase 1: The player may Normal Summon or Set a monster, activate cards and effects that they control, change the battle position of a monster (provided it was not summoned this turn), and Set Spells or Traps face-down. Battle phase: The player may choose to attack their opponent using any monsters on their field in Attack Position. Depending on the position of opposing monster, the attacking monster's ATK points are taken into account against the opposing monster's ATK or DEF points. If both monsters are in Attack Position, the monster with fewer ATK points is destroyed and its owner takes life point damage equal the difference between both monster's ATK points (if both monsters have equal ATK points, they are both destroyed and no damage is taken, unless both of their ATK points are 0, in which case neither is destroyed). If the opposing monster is in Defense Position and has fewer DEF points than the attacking monster's ATK points, it is destroyed and the owner takes no damage. However, if its DEF point is higher, the attacker takes life point damage equal to the difference between the two values. If the defending player has no monsters defending them, a Direct Attack can be performed, with the defending player receiving life point damage equal to the attacking monster's ATK points. The player can choose to not enter the battle phase and instead go to the end phase. Main phase 2: The player may do all the same actions that are available during main phase 1, though they cannot repeat certain actions already taken in main phase 1 (such as Normal Summoning) or change the battle position of a monster that has already been summoned, attacked, or had their battle position changed during the same turn. End phase: This phase also exists for card effects and maintenance costs that activate or resolve during this specific phase. Once this phase is resolved, the player ends their turn.
 * The player who begins the game does not draw a card from their deck during the draw phase and cannot enter the battle phase during their first turn.

Card types
Gameplay revolves around three types of cards: Monster, Spell, and Trap cards. Monster cards are monsters used to attack and defend against the opposing player, mainly for the purpose of damaging an opponent's life points. Spells, which can either be played from the hand or set for later use, provide various effects such as altering a monster's strength, drawing additional cards, or removing an opponent's cards from the field. Traps are cards that are set on the field in advance and activated in later turns when certain conditions are made, such as when an opponent targets a player's monster.

Monster Cards
With some exceptions, a typical monster card possesses ATK and DEF points which determine its attack and defence power in battles, a level represented by stars, with more powerful monsters typically possessing higher levels, an attribute that certain effects may react to, and a description listing the monster's types and any effects or summoning conditions they may possess. Monsters are summoned to the field through three main categories of summoning; Normal, Tribute, and Special. Once during a player's main phase, players can choose to Normal summon a level 4 or lower normal or effect monster from their hand in face-up attack position or face-down defence position, or Tribute summon a level 5 or higher monster by tributing one or more monsters already on the field. Special summons are performed by utilising card effects or fulfilling the conditions of other summoning methods, such as those used to summon cards from the extra deck, and can be performed as many times as possible if the conditions are met.

Normal Monster: A monster with no effects of its own, instead having a flavour text. Stored in the main deck and can be normal, tribute, or special summoned. Effect Monster: A monster that possesses at least one effect. Can be summoned in the same manner as normal monsters. Ritual Monster: Stored in the main deck, these monsters can typically only be special summoned by using a ritual spell card and tributing required monsters listed in its instructions. Fusion Monster: Stored in the extra deck, these monsters are summoned by utilising cards with a "fusion" effect, such as polymerization, and tributing monsters listed in the monster's description. Synchro Monster: Stored in the extra deck, these monsters are summoned by tributing from the field a tuner-type monster and one or more non-tuner-type monsters whose levels equal the level of the synchro monster being summoned. XYZ Monster: Stored in the extra deck, these monsters possess ranks as opposed to levels, and require two or more monsters whose level is the same as the XYZ monster's rank. These monsters become the XYZ monster's "overlay units", which can then be sent to the Grave Yard to activate effects. Pendulum Monster: Variations of other monster types which, if sent from the field to the Grave Yard, are placed face up in the extra deck instead. Pendulum monsters can be placed in pendulum zones in the leftmost and rightmost spell/trap zones, where they can utilise pendulum effects. When both pendulum zones contain pendulum monsters with differently valued "pendulum scales", players can perform a pendulum summon during the main phase to summon multiple monsters from the hand and face-up pendulum monsters from the extra deck whose levels lie between the two pendulum scale values. Link Monster: Stored in the extra deck, link monsters have link values instead of levels and can only be played in attack position. These are summoned by tributing one or more monsters on the field that meets the summon requirements, with link monsters able to be used as multiple tributes depending on its link value. Link monsters feature arrows which, when pointed towards other zones on the field, allows additional link monsters to be summoned outside of the extra monster zone. Link monsters may also possess effects that can be used when another card is a linked zone.

Spell Cards
Spell cards are magical spells with a variety of effects, such as reviving destroyed monsters. They can be played from the hand during a player's turn or placed faced down for activation on a later turn. There are six types of Spell Card:

Normal: A spell that can only be activated during the player's main phase. Quick Play: A spell that can be activated from the hand at any time during the player's turn, or can be set and activated during an opponent's turn. However, they cannot be activated the turn they are set. Continuous: A spell with a continuous effect that remains until conditions are met or it is destroyed. Equip: A spell that is equipped to a monster, providing it with support effects. It is removed if the monsters leaves the field or is set face-down, or the card is destroyed. Field: A spell that is placed in a player's field spell zone, which affects the entire field. Each player can only have one field spell in play at a time. Ritual: A spell that is required to summon a ritual monster.

Trap Cards
Trap cards have to be set on a player's field face-down and can only be activated after the turn they were set has passed, including the opponent's turn. (Quick play spells, when set, have the same rule.) They are generally used to stop or counter the opponent's moves, and come in three varieties.

Normal: A standard trap that is discarded once its effect resolves. Continuous: A trap that remains on the field until destroyed or its conditions are met. Counter: A trap that is activated in response to the activation of other cards.

Monster Cards

 * Haru Ranman 3Star (ATK 0, DEF 1800)(Self Destruct)
 * Snake Princess Anaconda 4Star (ATK 1400, DEF 1000)(Poison Viper One Flash Slash)
 * Centaur Aya  (ATK 1600, DEF )
 * Dragon of Earth''
 * Dragoon Aya (Combination of Centaur Aya and Dragon of Earth) (ATK 2600, DEF 2100)(Spiral Shocker)
 * Dullahan, Seeker of the Cards 8Star
 * Fen of the Forest 5Star (ATK 2600, DEF 2100)
 * Brutal Eyes Jade Dragon 8Star (ATK 3000, DEF 2500)(Destruction Blast Scream)

Spell Cards

 * Reverse Snake Mask (attaching to Snake Princess Anaconda increases her power by 800 points)

Trap Cards

 * Emergency Combination (Activated when under attack, combines two monster cards to form a new monster)
 * Inferno Storm (Quick Play)(Activated when taking 3000+ damage, makes both parties remove all monster cards from their decks)

Trivia

 * Duel Monsusus is a parody of the real-world card game.
 * As stated by Sekmeti, Mummies decide everything through card dueling.
 * Kimihito Kurusu was the Kanto Regional Tournament High School division winner during his days in high school.
 * As Kimihito, his homestay girls and Sekmeti note in Chapter 82, the classic style of Duel Monmusus is much easier to understand than the modern style, since the new cards can have 3 or 4 effects and the small font means that just reading everything on the cards is a challenge. Mr President also brings up these issuses when he desperately tries to learn the rules of the card game in preparation for his duel with Sekmeti.