Plague Inc. in normal mode, the difficulty behind the "parasite" - the parasite - is not particularly difficult. When playing in Brutal mode, accordingly, the tactics remain the same. Of course, everything will be rather slow, as when passing through a fungus, when you first have to wait for the infection of the whole world. However, with the help of special genes obtained for completing the previous levels, you can slightly speed up the process.
Steps
Part 1 of 4: Getting Started

Step 1. Start a new game
After starting the game, select the “Parasite” mode.
If you already have a previously saved game, it will be overwritten and no longer available. Select Brutal Mode, then name your disease

Step 2. Change the disease gene code
Now you can add special genes to your disease, obtained for completing the previous levels.
- Of course, you can either follow the advice given in this article, or at your own discretion.
- In the DNA Gene menu, select the “Cytochrome Surge” gene - for activating orange bubbles you will receive more DNA points.
- From the Travel Gene menu, select “Teracyte,” which increases the chance of ground spread of the disease. When you have enough infected, the process will begin.
- In the Evolution Gene menu, select the “Sympto-Stasis” gene. Yes, it will make your disease easier to cure, but the cost of genes will not increase, which is an extremely important part of a winning strategy. In addition, since we will be playing on a stealthy tactic, there is no point in worrying about the treatment.
- From the Mutation Gene menu select “Genetic Mimic”. This will make the disease more difficult to cure, which will compensate for the lack of Sympto-Stasis.
- Finally, from the Enviroment Gene menu, select the Extremophile gene. A small bonus in all climates won't hurt your virus.
Part 2 of 4: First appearance

Step 1. Start in India
Many players have given their hearts to this particular country, because a huge population, poor medicine, a warm climate, as well as ports and airports are the secret of success! China may still be good, but not always - sometimes diseases develop in it very slowly.
- If you started in India, the first country to be infected is likely to be China. After that, the disease will spread faster and more efficiently, as there will already be enough sick people in India.
- After choosing your starting country, activate the red and yellow bubbles.
- Do not forget to speed up the passage of time (button at the top right).

Step 2. Buy the Symbiosis gene
Remember, each disease has its own unique characteristics that give it a distinct advantage. In parasites, this is Symbiosis, the ability to mutually beneficial coexistence with the carrier, due to which the disease escapes public attention to the last. This gene must be developed to level 3.
- Keep activating bubbles, collect DNA points.
- Until you develop Symbiosis to the latest level, don't buy either symptom genes or genes for transmission.

Step 3. Buy the Cyst and Anaemia genes
So you have Symbiosis Level 3, which means it's time to buy the Cyst and Anaemia genes. They can be found in the Symptoms tab in the DNA window.
- Cyst is responsible for the formation of painful tumors filled with pathogens. These tumors have a small chance of breaking through and, consequently, causing infection in new people. This symptom increases the contagiousness of the disease, to put it simply.
- Anaemia is responsible for the decrease in red blood cells and hemoglobin in the blood, which leads to hypoxia - oxygen starvation - of the organs. This gene also improves efficiency.
- Typically, the development of symptoms early in the game leads to the development of a cure. Luckily for us, Symbiosis makes Level 1 and 2 symptoms less noticeable.

Step 4. Buy the Air and Water genes
Since we have bought genes that increase infectivity, we must continue to develop in this direction! Since tumors have a chance to break through, this is especially true.
To make the disease even more infectious, buy the Air and Water genes. They can be found in the Transmissions tab. The Air gene should be developed up to the 2nd level, and the Water - only up to 1

Step 5. Withdraw high mortality symptoms
There is a definite chance that your illness will mutate and develop this or that symptom. If this is a level 1-2 symptom, then leave it (you will not spend DNA points on this anyway). Nevertheless, if suddenly your illness has acquired an exclusively lethal symptom, it should be canceled.
The lethal symptoms alarming the public and trigger the process of finding a cure that can lead to failure. Keep lethality around zero for now
Part 3 of 4: Defending the Disease

Step 1. Buy the Drug Resistance gene
Even though your disease cannot be transmitted only by the dead, it still spreads slowly. Why? The answer is simple - drugs. People use them, and drugs are killing your disease!
Enough tolerating this! Buy the Drug Resistance 1 gene from the Abilities tab and end this genocide! After that, your disease will spread faster, especially in poor countries

Step 2. Buy the Cold Resistance gene
Climate is one of the obstacles to every disease. Develop the Cold Resistance gene to level 2.
- This will strengthen your parasite and allow it to spread faster in colder countries like Canada, Greenland, etc. And don't forget to cancel lethal symptoms!
- There is no point in buying the Hot Resistance gene. Starting in India, you have made your disease immune to the effects of warm climates, so save your DNA glasses.

Step 3. Buy the Hypersensitivity gene
If you do not have it, buy it, because this gene significantly increases the infectiousness of the disease.
After that, you can return to the game and accumulate DNA points until all nations are infected. However, you can save even until the message “There are no healthy people left in the world” (there are no healthy people left in the world)
Part 4 of 4: Let the World End Begin

Step 1. Buy basic lethal symptoms
Having received the message that there are no healthy people in the world, for now, start playing for high stakes.
Buy the following symptoms in the Symptoms deposit: Paralysis, Total Organ Failure and Coma. People will start dying, the medicine will start to be created

Step 2. Use extra DNA points
When the population of planet Earth begins to decline rapidly, you will receive a lot of extra DNA points. They are worth buying Internal Hemorrhaging, Hemorrhagic Shock and Necrosis. You don't have to worry about the medicine.

Step 3. Nevertheless, keep the progress of the drug creation under control
All peoples of the world will unite their efforts to find a cure. This can be prevented by using the Genetic Hardening Ability and Genetic Reshuffle genes.