In Pandemic 2 there are 2 gameplay modes, realistic and relaxed. Realistic is obviously more challenging then relaxed. It's possible to choose between a virus, a bacteria and a parassite. Your choice will greatly increase the infectivity, lethality and visibility of your desease. Your infection will spread automatically through neighboring countries, airports and harbours. There are 21 countries and It'll be very hard to kill the entire world population. Once you're discovered the mankind will try to develop a vaccine, at that point you'll have 2 chances: The time needed by the mankind to develop the vaccine depends from the number of active hospitals, if you shutdown all the hospitals the vaccine will never be completed. Alternately, If your drug resistance is high enough, you have a chance to resist the vaccine.
In order to play this game, you are required to install the Adobe Flash player.