Start a normal non-scenario game of Prion under the casual difficulty setting. Prion can slow down the cure forcing a longer game. Start in Saudi Arabia. Then, evolve the following in order as soon as possible: Air 1 and 2, Water 1, Neural Atrophy 1, 2, and 3, Drug Resistance, and Genetic Hardening 1 and 2. Note: Devolve every mutated symptom as soon as it appears. Evolve the following symptoms: Coughing, Sneezing, Pneumonia, Cysts, Hyper Sensitivity, Abscesses, Insomnia, and Paranoia. You will have to wait at this point, devolving all mutated symptoms. Even if the symptom is non-lethal it must still be devolved. Immediately pop the cure bubbles as they appear. If the cure progress reaches 75%, immediately evolve all three Genetic Re-Shuffles. You will eventually see the message "CDC teams hunt patient zero" followed after a few months by "CDC teams close on patient zero". Evolve the following symptoms immediately: Anaemia, Haemophilia, Internal Haemorrhaging, and Hemorrhagic Shock. They should begin killing the population at a decent rate. Do not have any more lethal symptoms, as you will need time for the final pop-up to appear. After nearly half the world us killed, the message "CDC fails to identify patient zero" should appear.