When you first start out in the game, there will only be one plague type available: Bacteria. The 6 other plague types can be unlocked in progression. The order of unlocking is as follows: Bacteria -> Virus -> Fungus -> Parasite -> Prion -> Nano-Virus -> Bio-Weapon. Unlocking the Neurax Worm is more demanding, though. All plague types can unlocked through in-app purchases. Note that beating any game on casual difficulty will not unlock the next plague type.

The 3 cheat plague types are the ultimate reward for the most experienced and highly strategic players. They allow for these players to "play" around with the world through the several cheats available. Unfortunately, only one type of cheat can be activated at any one time. The cheat plague types cannot evolve any special abilities of the 7 standard plague types (In order, Bacteria, Virus, Fungus, Parasite, Prion, Nano-Virus, Bio-Weapon) or the Neurax Worm. The cheat plague types will evolve transmission traits and symptoms identical to the 7 standard plague types. Here is the breakdown of what each cheat plague type do. Immune Plague - Your Plague cannot be cured; Cure research progress stops at 99%. Hidden Plague - Governments of nations are unable to take actions to stop the plague in any way; This means governments cannot prevent the transmission of your plague. Unlimited Plague - You will start the game with 2,000 DNA points, which is enough to evolve every single trait, be it transmission, symptoms or abilities.

Unlock the Necroa virus by beating all the standard plagues and the Neurax Worm on Brutal Difficulty.

You can unlock the next type by clearing the stage before it on Normal or Brutal difficulty.

This can be unlocked via completing the game on Brutal.

This simple exploit of current game mechanics makes a joke of one of the harder disease types! (When playing nano-virus, they are aware of and curing your virus from the start) It requires only that you have unlocked (and equip) the 'Sympto-Stasis' genetic code upgrade when setting up your game. Genetic codes are unlocked by winning a game on any difficulty with any virus type. With Sympto-stasis equipped, the cost of symptoms does not increase as you evolve them. The nano-virus has 2 symptoms that actually -GIVE- DNA when you take them, and this virus type has a natural ability where devolving costs don't rise (default cost of devolving gives 2 DNA). These are Insomnia and Paranoia. Simply buy those 2 and then repeatedly devolve/evolve paranoia for unlimited, free DNA.