Bacteria
Bacteria is the plague type least likely to spontaneously evolve, meaning it’s easier to keep control of it as it spreads around the world. Bacteria’s unique ability, bacterial resistance, provides general environmental protection, but it’s not as effective against hot and cold as heat resistance and cold resistance. If you’re struggling in an extreme environment and have already maxed out resistance to either heat or cold, that’s when you put points into bacterial resistance.
Virus
Virus stands apart from other plague types because of how it mutates rapidly and costs DNA points to devolve. Investigate every pop-up window about spontaneous changes in your virus, especially in the earliest stages of games. Viral instability enhances the number of mutations, so avoid putting points here until work begins on a cure. If you’re looking to set speed records for victory, start with a virus.
Fungus
A fungus is the most difficult plague to spread, which makes investing in its unique abilities (spore burst, spore eruption, and spore hardening) an integral part of every fungus game. The evolution gene option patho-stasis seems tailor-made for fungus, but you must be on top of devolving potentially lethal symptoms if you choose it.
Parasite
A parasite plague likewise leans on its unique ability, symbiosis. Symbiosis negatively affects your severity score, allowing the safe addition of infective symptoms in the early stages of your game. A parasite won’t evolve on its own often, but devolve anything that’s potentially lethal until you’re set up to start with the killing.
Prion
Prion’s unique ability, neural atrophy, impairs neural activity in humans and increases the time before research into a cure will begin. Early DNA points should go entirely to ways to increase transmission, which includes transmission options and mild symptoms like coughing and sweating. Devolve spontaneous mutations until your prion reaches every country. At that point, dump your built-up DNA points into fatal symptoms.
Nano-Virus
A nano-virus plague starts with a big disadvantage: The cure (actually a computer code to deactivate it) is being worked on as soon as you select patient zero. You should have a number of genetic code options at this point. Two good choices are genetic mimic to slow the cure and metabolic jump to get more DNA from popped bubbles. Spend early DNA points on anything that slows discovery of the cure and boosts transmission of the plague. Nano-virus has two special ability trees, which are both focused on slowing the development and implementation of the shutdown code. Invest in both early. Build up DNA points while the nano-virus spreads, then spend heavily in a rush to make it lethal.
Bio-Weapon
A bio-weapon gradually increases its lethality without external input, which explains why its unique abilities are all related to lowering its lethality. Nucleic acid neutralization resets lethality to zero, so save sufficient DNA points in case of emergency. Check the lethality level in the Disease menu often; you won’t be prompted by the game! Keep your bio-weapon in check and spend just enough DNA points to get it spread around the world. Once the world is infected, get the unlock annihilate gene. It’s vital that the plague is everywhere before you make this purchase. It’s so effective, it may kill the infected before they can reach a country that’s still healthy.