Bacteria - most common cause of plague. Unlimited potential 

Virus - a rapidly mutating pathogen which is really hard to control

Fungus - fungal spores struggle to travel long distances without special effort

Parasite - parasitic life style prevents DNA alteration from everyday infection 

You or the ai can steal or gift infectivity, lethality and visibility

Keep track on the AIs progress and evolves

Co-op: work with the ai to kill everyone 

VS: work against the ai to kill everyone 