Heredity & Trait Inheritance

Reproduction is an important goal for nearly all living things in OC , and it’s how virtually all new living things come to be. Excluding world generation, nothing “spawns” by magic in OC . As such, the mechanics of creating new living things are extremely important, both to human expeditions and the greater composition of OC worlds.

On some fundamental level, all living things are physical products of their ancestors, and the same holds true in OC . Though simplistic in approach, OC  emulates this by way of its heredity system. When two living things reproduce, their traits are passed on to their offspring, enabling populations to adapt and change over the course of generations.


A herd of fat unicorns, welcoming a new member. Note the age of the inspected creature, making it a baby.


  • All living things in OC  reproduce. It’s how new NPCs come to be.
  • Parents pass on their traits to offspring.
  • It’s important to remember that, from a physical perspective, humans are creatures. They’re a very special kind of creature, but they’re bound by the same physical rules as other creatures. As such, inheritance rules apply to OC’s humans as well.
  • OC’s model of genetics works via a simplification (a tremendous one) of real world mechanics.
    • Most traits exhibited by living things in OC are complex, meta-sorts of traits in the real world.
    • Height, weight, strength, stamina, and other measures are the result of complex interactions of many, many genes. These things aren’t yet fully understood in real life. Attempts to model complex traits like this by simulating real inheritance is far outside the scope of OC.
    • What we can do, however, is to model inheritance of these traits with a higher level abstraction. In general, we can get fairly compelling results by averaging trait values of parents and adding a bit of +/- randomization. If a tall woodgrunt produces offspring with a short woodgrunt, you’ll probably wind up with a bunch of roughly medium height woodgrunts.
    • OC’s heredity model also accounts for mutation. This adds an element of unpredictabilty to the process and can help populations change quickly under certain circumstances.
    • Inheritance of traits with discrete values (like eye color and hair color) follows different sets of rules.
  • Inheritance makes it so that populations will change over time. Whichever NPCs happen to reproduce successfully, be it through combinations of advantageous traits, or dumb luck, will define a species’ makeup in the future.

Reproduction & Trait Inheritance


A fat unicorn male, undertaking the journey to reproduce.

Nearly all living things in OC  aim to reproduce, and it’s one of the most important, highest priority goals for any mature creature. The mechanics of reproduction itself are very simple. In general terms, a creature will seek out a partner of the same species and opposite gender, travel to it, bump into it, and the act is complete. While the overall concept itself is simple, variations among species can change different aspects of the process in different ways. Partner selection can be complex, the journey to a partner can be perilous, and many NPCs die before having the opportunity to reproduce. Reproductive success is never assured for any individual. In many ways, it’s the ultimate challenge for each NPC.

If two individuals do complete their reproductive behaviors, the female will become pregnant. The pregnancy lasts for some species-defined gestation period, after which a new member of the species is born. In almost all ways, the new entity is a product of its parents. Its traits, physical characteristics, and much more are factors of its parents’ traits, coupled with some variability for mutation.

The end effect of this system is that, as time passes in a world, the general characteristics of its species change according to which members have managed to reproduce. As long as the population of the species is sufficiently large, it will tend to undergo changes that make it well suited for its particular environment on its particular OC world. This doesn’t always mean that species will get bigger, faster, and stronger. To the contrary, those traits impose larger metabolic requirements, which is often disadvantageous. In environments where food becomes scarce, if bigger individuals are starving to death, their leaner counterparts will probably reproduce more.

Dumb luck plays a huge role on the individual level, and if a species’ population is small, its influence is felt strongly on the macro level. Often, a particular individual just happens to be at the right place at the right time, and it manages to reproduce. Sometimes a fantastic specimen will just happen to have its leg broken in a fight while hunting, leaving it crippled and likely to die. A woodgrunt might happen to kick a tremendous frostbull in just the right way, ultimately killing it off and leaving it without a genetic legacy. Chance. Happenstance. A million and one factors, playing out every moment in a world, determine which individuals win and lose.

While these sorts of chance events are extremely important at the individual level, they do tend to balance out across large populations, which is what ultimately makes the process work. Still, mutants with extremely interesting combinations of traits can occur, and the effect of chance on the reproductive success of these individuals can have drastic effects on populations over the long term.

Ultimately, I find it very fun to just let a world run for a long period of time and watch all the changes accumulate in the fauna composition of world. The emergent, macro effects of a system that’s fairly simple at its core are very fun and yield all kinds of gameplay consequences.


Perhaps the most direct, gameplay-centric consequences of the trait inheritance system are on your expedition. Again, from a physical standpoint, humans are just a special sort of creature in OC. They’re bound by all the same physical rules, including those of trait inheritance. This means that, when your personnel pair up romantically, their kids are going to be (more or less) like their parents.


A new person in OC.


Physical properties of the family. Compare the child’s traits to those of the parents.


Personality tendencies of the family. The baby isn’t capable of behaviors to express these, but these inclinations become important as an adult.

This has extremely important, long term effects on the composition of your expedition. Eventually, all of your expedition’s original personnel are going to grow old and die. The sort of people that you’re left with, several generations down the road, can depend entirely on the romantic tendencies and behaviors of past generations. As an expedition manager, the extent to which you can control these tendencies varies and can be somewhat limited. However, modification of cultural parameters can influence personal preferences on the individual level, which can have an effect at the group level.

For example, policies and media designed to make smart people seem cool will help their reproductive chances. But these sorts of moves can have unintended side effects. If you produce an entire society of only people with genius level intellect, the result will be like the Cyprus Experiment from Brave New World. No one will want to work as a miner or a farmer (see the “Trait Effects” example from the personality article for details), and you’ll wind up with a bunch of dangerously smart malcontents.

The point here is that you have to be judicious with the choices you make in promoting and discouraging aspects of your expedition’s culture. The long term effects, which are the ultimate manifestation of the trait inheritance system, can wreck an expedition over the course of generations. And it’s precisely these sorts of emergent mechanics that make the system thought provoking and fun.

Posted in NPCs