Before a player starts their game, they can insert Genetic Code. These genes allow personalization of pathogens by providing boosts to how one infects people, reacts to different environments, acquires DNA, and just the playstyle in general of your pathogen.
Every time a player wins a game with a standard plague, they unlock one of the 25 genes, regardless of the difficulty level. The same goes for victories in the Neurax Worm. However, the other special plagues normally unlock one of their special genes.
There are five different types of genes: DNA Genes, Travel Genes, Evolution Genes, Mutation Genes, and Environment Genes. Players can only have one of each type of gene per game, meaning that there are a large number of different genetic combinations that one can use for any disease (3,125 to be exact) . There are exclusive genes for Necroa Virus, Simian Flu, and Shadow Plague. On Android, you must buy the premium version for $1.00 in order to use the genes that you unlocked.
Beating a Simian Flu level likely unlocks a Simian/Artificial Gene
Beating a Shadow Plague level likely unlocks a Shadow/Flight/Blood Rage Gene
Here is a list of some genes on Multiplayer games. Some of the genes on Multiplayer are VS Mode exclusive. This list is less outdated than it was, but is still none-the-less incomplete.
Hydrophobe: Gives your plague a bonus in arid climates, but a penalty in humid climates.
(+1.33 arid, -1 humid)
Xerophobe: Gives your plague a bonus in humid climates, but a penalty in arid climates.
(-1.33 arid, +1 humid)
Urbophobe: Gives your plague a bonus in rural environments, but a penalty in urban environments.
(-0.67 urban, +0.57 rural)
Rurophobe: Gives your plague a bonus in urban environments, but a penalty in rural environments.
(+0.67 urban, -0.57 rural)
Pharmaphile: Gives your plague a bonus in wealthy countries, but a penalty in poor countries.
(+0.12 rich, -0.5 poor)
Pharmaphobe: Gives your plague a bonus in poor countries, but a penalty in wealthy countries.
(-0.12 rich, +0.5 poor)
Frigophobe: Gives your plague a bonus in hot countries, but a penalty in cold countries.
(+0.1 hot, -0.16 cold)
Thermophobe: Gives your plague a bonus in cold countries, but a penalty in hot countries.
(-0.1 hot, +0.16 cold)
Benign infection: Your plague is harder to cure but you start with less DNA.
Unstable inception: Get bonus DNA (+9) at the beginning, but your starting country will be selected randomly.
Base Hydration: Your plague can mutate transmissions and abilities, but costs to evolve will increase quickly.
Innocent Infection: Your plague will find it easier (+50%) to infect people that are already infected by other diseases, but harder (-50%) to kill them.
Deadly Disinfectant: Your plague will find it easier (+50%) to kill people that are infected by other diseases, but harder (-50%) to infect them.
VS mode Exclusive Safe house: Get more DNA (from 2 to 4) from bubbles in your starting country, but your opponent gets bonus DNA (+6) when it is discovered.
VS mode Exclusive Search and Destroy: Get a DNA bonus from finding your opponent's starting country. The bonus decreases the longer it takes. If you find your opponent's starting country in 0 days, the bonus will be 40 DNA points. The bonus will be decreasing by 0.13 per day.
VS mode Exclusive Peekaboo: See which countries your enemy has infected but gain less DNA (-6) when discovering thier starting country.
The Mutation Genes,(Base Oxidisation & Base Hydroylsis) Evolution Genes, (Sympto-Statis, Patho-Statis, & Trans-Statis) And Multiplayer genes have good and bad sides.
Neurax Worm is the only special plague that dosen't have its own special genes.