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Creature-Breeding Mechanic

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No one better tell him about the platinum ones...

In a game in which friendly or tameable creatures play an important role, sometimes a player will find themselves needing more or better critters than what they can find naturally. Reasons for this could vary based on the goals of the game, but the solution to the problem is always the same: you breed the beasts you have in order to get your desired result. Some games may instead opt for a "fusion" system that causes the two parent creatures to disappear, but the idea behind it is very much the same.

In-game breeding systems involve putting two compatible creatures together in order to obtain offspring that take after one or both parents. An extremely basic system would result in offspring that look just like one of the parents. However, more complex systems can include multiple traits that can be bred for, complicated rules for inheritance, and perhaps even methods for producing Mix-and-Match Critters.

Although this trope can fit comfortably into many different genres, it is most often found in RPGs and simulation games. In the former, it often plays out as a sort of Lamarckian Min-Maxing, in which the player carefully picks breeding pairs, possibly over several generations, in order to obtain a highly optimized creature at the end. Simulation games are more likely to have highly complex breeding systems, to the point that Breeding Sim has become a recognizable subgenre in and of itself, usually found in the form of browser games.

Hot Skitty-on-Wailord Action is a separate trope, but overlap with this one is not uncommon. For tropes that may result from a breeding system, see Gender Equals Breed, Patchwork Kids, All Genes Are Codominant, Super Breeding Program and Hybrid Power. Fusion-based versions bear some relation to Item Crafting.


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    Action Adventure 
  • Sonic Adventure and its sequel both include Chao gardens. Chao may be trained and any two may be crossed, with the usual Lamarckian mechanics coming into play. This doesn't affect anything outside of the garden, though.

    Browser Game 
  • BeastKeeper is a pet game and breeding sim. Both positive and negative traits can be inherited by offspring, so players must be careful to avoid breeding pairs that may produce weak, stupid, or otherwise undesirable children.
  • Celestial Vale and its sister games have/had breeding systems with differing levels of complexity.
    • Celestial Vale in particular had three breeding systems during its lifespan, with an extremely complicated genetics system, which only the site's programmer fully understood. 1.0's DNA system was short-lived due to its flawed execution resulting in some colors being disproportionately common as breeding results. For the rest of 1.0's lifespan, breeding results could be influenced by the colors of a creature's ancestors, with more recent ancestors having greater chances of their color being inherited. 2.0 brought DNA back, but with so much added complexity that only the site's programmer fully understood how it worked.
    • Valley of Unicorns: Breeding results are usually semi-randomized, but some rare colors have unique inheritance behaviors that can encourage purebred lineages or breeding at specific times of the month.
  • Dragon Cave is a game that simply involves collecting dragons. Most of these dragons can breed, and most of the time baby dragons will grow up to be identical to one of the parents. To spice things up, there are a few hybrids and alternate sprites that can only be obtained through breeding, and some egg varieties can only be laid at certain times of year. A dragon's pedigree is viewable, and the value of a dragon has a lot to do with how visually appealing its pedigree is.
  • Flight Rising is another game about breeding dragons. Dragons can come in several breeds and colors, and "genes" can be added to a dragon in order to give it special markings and features. All of these traits can potentially be passed down, with inheritance calculated differently for each.
  • Khimeros is a virtual pet game that features breeding.
  • Strangelings involves the breeding of fox-like creatures.
  • Wajas is an online pet game that revolves entirely around breeding the eponymous creatures. Breed, color, markings, and mutations are all traits that can be bred for. There's an enormous range of options and no predefined goal, so it's rare to find two players who are trying to breed for the exact same result.
  • OviPets is built around this trope. There are over 25 species of pets to breed and add mutations to.
  • Lioden: A major focus of the game is breeding the lions in your pride. Almost every aspect of a lion's appearance can be inherited through breeding, and in fact some bases and many markings can only be gotten only on a lion through inheriting the gene for them from a parent.

  • The Player-owned Farm in RuneScape allows players to raise and breed animals with the Farming skill, starting with rabbits and chickens all the way to Yaks and Dragons at higher levels, while The Ranch out of Time expansion allows for animals native to Anachronia island, including frogs, salamanders and Dinosaurs.
  • Star Trek Online has tribble breeding, done by either leaving the tribble in inventory with particular foods, or by duty officer assignments found in your ship interior. The former creates a new tribble, the latter transforms your old one. Different tribbles grant different buffs: for example feeding a tribble ketracel-white will produce a tribble that buffs your damage against Jem'Hadar.

    Role Playing Game 
  • Dragon Quest Monsters: The first several games have a breeding system in which offspring may not have a similar appearance to their parents, but they will inherit their parents' powers. Dragon Quest Monsters: Joker and its sequels changed this to a Fusion system, with polarity replacing gender.
  • Final Fantasy:
    • Final Fantasy VII: Acquiring colored chocobos requires you to breed the chocobos you've captured and leveled up. Some players might be put off by the fact that related chocobos can be bred together, but this isn't too unlike animal breeding in real life. VG Cats examined this in its usual manner.
    • Final Fantasy XIII-2 lets the players infuse one of their summoned creatures (which fill out the third party slot in battles) with another. This destroys the latter but transfers some of its special abilities to the former, effectively creating a stronger breed.
  • Jade Cocoon has a Merging mechanic that allows you to fuse two minions together. The resulting minion has the body-shape of the first 'parent', the color scheme of the second, and the special attacks and elemental attributes of both.
  • Oreshika: Tainted Bloodlines uses this for the human members of your clan, who are forced to live a condensed life span of only two years, roughly. To get around this, your clan members are able to create divine (but still cursed) children with gods. There are at least a hundred gods you can perform the rite with, and the children will inherit traits from both the human and god parents. Occasionally, the child will even have unusual visual traits from their parent god, for instance, performing the rite with a kitsune god might result in a child or grandchild with fox ears.
  • Pokémon has a breeding system that has grown in importance and complexity over the years. Pokémon are divided into a large number of "egg groups" based on overall physical similarities, such as Monster (large saurians), Human-Like (humanoid bipeds), and Mineral (made of inorganic substances). Each Pokémon belongs to either one group or two and can only breed with Pokémon with which it shares a group. In cross-species pairings, the mother determines the species of the offspring. An unusual case is the shapeshifter Ditto, which can be bred with any Pokémon to produce offspring of its partner's species. There is also a complicated system to determine whether the offspring inherits any starting moves, based mainly on the parents' movesets, which can be used to hatch Pokémon that know moves that cannot be learned without special tools or which their species cannot learn in any other manner. This system can be used to obtain rare species and palette swaps, and it's also essential for producing high-quality teams for competitive play.
  • Shin Megami Tensei: Demons can be fused with one another, or in some games simply sacrificed, to create new demons. As, after a while, the leveling requirements increase far too sharply for demons to remain useful, unlike the human characters, this is the only alternative to negotiating with more powerful creatures.
  • Temtem: The breeding mechanic allows the parents to pass down stats and techniques to their offspring, as in Pokémon, but it also has a stat called fertility. Each time a Temtem breeds, its fertility drops by one. Once at zero, it can never breed again. This is to discourage grinding.

    Simulation Game 
  • Hybridizing flowers in Animal Crossing fits the spirit of this trope, if not the letter. If two differently-colored flowers of the same type are planted close enough to each other, a new flower of an unusual color may grow nearby. The catch is, you can't use just any two different colors; each hybrid has two or three possible combos that can produce it, and some hybrids are prerequisites for others.
  • The humanoid monsters in Cloud Meadow can pass down traits (such as better stat growth or more efficient farming abilities) from parents to child, though there is a chance for genetic mutation that will either greatly improve or severely downgrade the result. Additionally, some color palettes are only natural for certain races, so crossbreeding is required to see all variants. Due to the nature of the game, the protagonist can also get involved, but only if they've never been a part of their partner's family tree.
  • Harvest Moon is a farming sim so it always features cow pregnancies and chickens laying eggs. Harvest Moon 3 and Harvest Moon: A Wonderful Life have male animals, unlike most titles, and thus it's possible to breed your own animals instead of using a "Miracle Potion".
  • In Let's Build a Zoo, if you have at least one male and one female animal of the same species in an enclosure, they have a chance to breed with each-other. Usually the offspring will look like one of the parents, but there's a rare chance they'll produce a different variant instead. You can speed this process up using the nursery.
  • The Monster Rancher series uses the fusion variant, with the resulting monster having traits from the "parents" and starting out a bit stronger than a monster generated from a disc.
  • Parkasaurus: If an exhibit contains two dinosaurs of the same species and opposite sexes, the player can place a nest in there. If the dinosaurs are happy enough, an egg will appear the next day, and it will inherit colours and traits from its parents.
  • This is a major draw for the Petz series. Puppies and kittens will inherit traits from both parents and some players have created custom breeds simply by breeding for desired traits using the available in-game breeds, without even using mods.
  • In Roots Of Pacha, you can breed livestock with the breeding pen by pairing two animals of the same species with a high enough friendship towards you. Their production quality, frequency, and movement speed are passed down to their offspring, and breeding them for several generations will evolve them into their domesticated counterparts (e.g. bison become modern-day cattle).
  • The sci-fi Farm Life Sim Verdant Skies has an interesting variant on this with both animals and plants. You can take genetic samples from wild animals and grow your own in a Uterine Replicator, and you can extract seeds from crops. In both cases, there are gene-splicing machines that allow you to edit the genomes of the animals and plants and discover which genes code for which traits, then mix and match until you have the traits you want. There are even achievements for breeding animals or plants with specific trait combinations.
  • One of the main points of Viva Pińata is its "romancing" system. Outside of one very specific case, romancing is only useful for producing more piñatas of species you already own. However, romancing is essential for meeting the population requirements that some wild piñatas have.
  • In Shepherd's Crossing, breeding farm animals is an important part of the gameplay. You have both male and female animals, and if a male animal touches a receptive female animal, she'll usually become pregnant. Many animals provide useful meat, female animals won't give milk if they haven't given birth, and you can breed animals in different colors. The second game shows when female animals are in heat, so you can isolate them if you don't want them to become pregnant.
  • The titular creatures of Wobbledogs will occasionally lay unfertilised eggs. The player can either hatch them right away, which results in a dog with the default appearance, or they can choose two dogs to fertilise it. The latter will open up a simulation which generates a litter with mix-and-matched features from the parents. The player can choose one, or continue breeding them for several simulated generations in order to get dogs with more mutations.
  • As a wolf in WolfQuest, your driving biological imperative is passing on your genes. The stats and diversity rating of you and your mate determine the stats and appearances of your offspring, which if they survive are playable to continue the cycle. The higher the diversity of the mate (up to 4 stars), the more desirable they are. One unique feature is that black-coated wolves will produce smaller, but more disease-resistant litters.
  • In Fallout Shelter you can leave a male and female dweller in the bedroom and they're have a baby, they'll always inherit one of their parents highest state at three where normally skills for new dweller top out at two

    Strategy Game 
  • In Fire Emblem: Genealogy of the Holy War, Fire Emblem: Awakening and Fire Emblem Fates you have the option to pair off the first generation to produce a second generation. What parents pair up influence the children's stat growths, skills and abilities, and in Awakening and Fates what classes they can reclass to. However, unlike most examples on this page, it's a part of the plot of the first two games: Genealogy spans decades and the second half of the game centers around the children (although it should be noted that should certain people fail to be paired up, there will be replacement characters), and the children in Awakening are time travelers sent to avert a Bad Future (again, note that technically you're only required to get Lucina, the others are recruited in optional paralogues).
  • In Disgaea 5, Innocents can be placed in the Innocent Farm to increase their levels and a pair of them can give birth to new Innocents, which is a much more efficient way to farm more copies late game. It's also the only way to get dual stat Innocents.
    • Disgaea 2 introduced the mechanic first with a special Innocent called "Mediator", which had a chance in each Innocent Town to wed two Innocents together, producing a Dual-Stat Innocent. However, this is reliant on both finding an innocent Town after each 10th floor and having the Mediator event show up.
  • In Massive Chalice, you must partake in a hero breeding mechanic, where you, as the immortal king of the realm, must decide which heroes and heroines defending the lands have to retire to their castles, intermarry and produce a new lineup of young heroes who inherit some of their old folks' powers and generally become stronger with each generation.

    Tower Defense 
  • War Dragons: You get new dragons by breeding the ones you already have. The frustrating part is that Epic and Rare dragons need multiple egg fragments to be obtained before they can be hatched, and you need 20 egg tokens per egg or fragment bred.

    Wide Open Sandbox 
  • ARK: Survival Evolved has a breeding system. In it, 2 wandering creatures of opposing sexes will fill up a female's mating bar. Provided they stand close together until the bar fills, the female creature becomes pregnant.
  • Minecraft has all sorts of friendly and passive mobs that provide utilities or materials that players may find useful. Since natural mob spawning can't entirely be controlled or relied on, there exists a breeding system that allows most animal-based mobs to produce babies. Breeding for most of these animals is very bare-bones, but horses have a more complicated system that involves colors, markings, and hidden stats.
  • Spore, with the twist that the player controls a single creature directly. Evolution is the goal in that stage of the game: you hunt around for bones that contain instructions for new body parts, then use acquired evolution points to append selected parts in the next generation of creature. In the space stage, there's also a "creature tweaker" that allows manipulation of any creature found in the game, but this is purely cosmetic with no influence on play.

  • Tamagotchi:
    • Starting with the Tamagotchi Osutchi and Mesutchi devices, players can introduce their adult Tamagotchi to another adult of the opposite gender to have them get married and produce new eggs to raise. Certain Tamagotchi characters can only be raised on even generations, so breeding is necessary if you want to see those Tamagotchi.
    • On the Tamagotchi m!x and Tamagotchi ON, Tamagotchis inherit traits from their parents rather than evolving into a random character as in previous releases, allowing the player some control over what their Tamagotchi will wind up looking like.

    Non Video Game References 
  • Awkward Zombie: One comic references the Fire Emblem: Awakening example, as Katie literally pushes Gaius away from Panne and forces him to marry Tharja, all so her daughter Noire has access to the Galeforce ability.
  • Homestuck: A central component of Sburb, the reality-warping Fictional Video Game that the characters play, is frog breeding. Each session's Space player is tasked with tracking down frogs of increasingly rare varieties, cloning them, and artificially hybridizing them. The ultimate goal of this is the creation of a Genesis Frog, an immense, galaxy-patterned amphibian that holds an entire universe within its body; entering this new cosmos is the final reward of a successful session.