Mutations

A mutation is an alteration in the nucleotide sequence of the genome of an organism, virus, or chromosomes. Mutations can result from natural errors during DNA or viral replication or repair, or exposure to external agents such as radiation or toxic waste. Mutations may also result from insertion or deletion of segments of DNA due to mobile genetic elements.

The Great War


The amount of radiation and biochemical agents released during, before, and after the Great War has led to major changes in the biosphere, on top of the devastating climate changes that followed in the wake of civilization's march to nuclear devastation. Its presence has induced widespread mutations in flora and fauna, leading to the emergence of giant versions of regular species. The radiation-induced mutation is behind many of the staples of post-War United States, such as radscorpions, geckos, spore plants, and brahmin.

Absorption, decay, and diversification


Some humans may also become mutated by radioactive exposure. Although most will die after exposure, a combination of factors can cause them to become ghouls, humans who resemble walking corpses and have extended lifespans. They are immune to the negative effects of radiation. A majority of ghouls are little more than shambling corpses, while a minority retain their faculties. Ghouls have a chance to become a glowing one or a glowing feral due to the accumulation of radioactive poisoning, subsequently emitting radiation and lacking body heat. Most mutated lifeforms are similarly immune to radiation but may become "glowing" by accumulating exposure, with a distinct green glow accompanying them, together with a radioactive "cloak" that poisons their surroundings.