Except in some scenarios, players can insert one of the genes from Genetic Code before they start their game. These genes allow personalization of plague, for example, by providing boosts to infectivity and DNA gain, increase/decrease the mutation rate, and so on.
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 Neurax Worm. However, the other special plagues can 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 $0.99 in order to use the genes that you unlocked.
Get more DNA from popping red, biohazard bubbles (The points given are random. There is a 6/13 chance that the player will get one more point per bubble. The DNA Points given by the red bubbles depends of the disease's severity.)
Get more DNA from popping orange DNA bubbles (In general, the gene tends to give the player a +1 DNA at the beginning of the game when the disease is basic and has not been found. When the disease is more complex, in particular the severity has increased, the gene gives the player more DNA per orange bubbles. The range that gives more DNA for the gene is random.)[1]
Give your plague a minor bonus in all environments (+0.2 arid, humid, rural & urban effectiveness)
Evolution Genes[]
These genes change the way your plague evolves. Note that these types of genes don't interfere with the Genetic Drift in Mega Brutal difficulty, which determines how much the amount of infected population should scale, although they are primarily designed to cut certain DNA point costs, especially early in the game.
The Multiplayer Mode adds unique genes that allow players to give certain advantages in a specific type of environment while making the plague less effective in others. These genes also include advantages of different mechanics such as making the player's disease kill people infected with other diseases faster, or making DNA bubbles that appear in the plague's country of origin score more points until the opponent finds the player's country of origin.
Glitches[]
In some versions of Plague Inc: Evolved, the player can save the game just before winning and reload it many times as needed to unlock all genes for a disease type in Genetic Code.[2]
Trivia[]
Some of the genes have good and bad sides. For some genes that make your plague easier to cure, however, some abilities and symptoms can override that effect.
Neurax Worm is the only special plague that doesn't have its own special genes.