Before you start, you will be given a choice on what you want to edit. There's no real reason to deselect anything, although this guide is here to cover all aspects.

It should be mostly simple to pick, if you haven't completed the game, it is not recommended to create scenarios just yet. Having beaten every disease on easy and mega brutal difficulties greatly helps you get a grasp on the difference of mechanics, effect of genetic drift, and etc.

Depending on your scenario, choose one of the following templates:

The first and least complex disease, easy to understand and very flexible.
If your scenario is broad, generic, or requires heavy editing, this is for you.

It offers the absolute base of plague inc's gameplay and is both the starting and final point of any scenario creator. Having only the most basic traits, it is a very balanced disease that's hard to screw up. Without heavy editing, however, can get boring to play.
The second disease, barely different from the bacteria, usually promotes chaotic, hard to stop or uncontrollable plagues.

If your scenario is still basic, but has a different, more open approach to infection, the virus is for you. Although it's not very different, it will be of help if you need slightly more punishing mutations, with them costing instead of refunding DNA and such. Most other aspects remain unchanged though.


The third disease, possessing poor country spread, but the ability of producing fungal spores. It is recommended to use for digital, or generally non-biological plagues.

For those who want to create anything along the side of a computer virus, some kind of fake news or etc, this is for you. The spores are very similiar to general internet spread going everywhere and will be useful templates later.

The fourth basic disease, (to be honest, really boring, promotes the same gameplay of hiding the whole time then killing everyone) with enough editing, can be turned into an interesting subsection of the Neurax Worm, with alternate paths of either stealth or open infection.

Quite an uncommon disease type to be used, as it does not possess many useful templates other than an outrageously easy to remake ability that lowers the severity. No real reason to go this though.

The fifth disease. Slow, painful, hard to cure and find. The prion is designed for long, strategic gameplay.

Hard to heal, hard to hurt. Quite useful for the degradation of the brain but not it's control. Not much more is there to be said.

The sixth disease, where the title completely speaks for itself. A mechanical plague that is found immediately after starting the game. Having cheaper base costs, high efficiency in all conditions, constantly fighting the cure. Obviously made for technological scenarios of any sort.

The Nano-Virus possesses very unique properties. It is extremely easy to spread around, and just as much to cure. It is very recommended to make fighting a cure something the player has to constantly invest in, but leave another half of their interest in the now easier infection.
The lack of a realistic (for now) scenario allows for a very broad range of possibilities in both traits and actions.

The final basic disease, a fight against yourself, trying not to kill your hosts. Puts constant pressure and makes disease very easy to find.

The constantly growing lethality forces a constant response (like the Nano-Virus) from the player, and just like the Nano-Virus, it is very easy to find, as deaths are extremely noticeable. Sort of close to the Necroa Virus, without the zombie creation. Promotes aggressive playstyle.




The first of the four special diseases, having vastly changed stats. Quite obviously, designed for manipulation, mankind enslavement, and other usage of possessed humans.

The Neurax Worm allows for a pretty comfortable creation of a 2nd ending, where you enslave humanity in a way. Due to it's nature, it is slightly more severe and easier to find, whilst also costing to devolve like the virus. Try to keep the traits sensical with how it behaves.

The second special disease, very engaging and requires constant on the spot thinking and quick calculations. Extremely good for any kind of resurrection or conversion scenario, allowing for very detailed attacks against humanity or any other group you make them into.

The Necroa Virus is able to create zombies, which decay over time. Although quite flexible, as of now I don't know a way to alter core attributes such as names of zombies and the base news of government actions against them, it can make unique scenarios have weird moments. (Pretty neglectable otherwise.)
Playtesting this template is extremely crucial, if it is easy to infect the whole world, the zombie part might not even come to play. Too little, and the zombies will die off instantly. If you are going to alter and add government actions or heavily edit symptoms, be very careful with what numbers you put into zombie strength, advantage and such. Same for Z com, as it can lead to either never ending or impossible to win/lose fights.

The third special disease, hard to edit without becoming nonsensical, however if your scenario is already about apes for any reason, it is very very well made and will offer huge variety.

As already stated, it is practically welded into place, if you try to considerably change it, you will end up with incohesive nonsense. Either completely unrecommended, or crucial.

The final special disease, shares the same problems as the simian flu, promotes a more patient and passive approach for the first half of the game (no plague, just fighting and farming points.).

Unengaging playstyle leads to uninteresting and repetitive gameplay with lack of variety. I do not recommend you to pick this template, but if you do, also keep track of vampire/Z com strength to not be overwhelming.

It is a simple process, to start you need to make the canvas in your painting software a size of 78x78, whilst not going above 50 KB in size.
For the icon of the scenario or any event pop-up, the requirements are:

In-game, icons have the ability to have icons, but keep in mind. When traits are evolved, their colors become inverted.

Any backgrounds that aren't removed will also weirdly stick out, so make sure not to let that happen.

Here is an example using a temporary drawing I made:
What it looks like before and after it's bought:

(Notice the colors.)

Icon overlays have identical requirements as icons themselves, keep in mind that you shouldn't make them too thin, too thick or allow any kind of pixels burning through the outlines.

• For most icons, use only white color, keep it simple, get rid of any weird border outlines.
  
• The color inversion can be used on purpose, allowing for more creativity.
  
• Keep icons centered and in place.

Creating custom transmissions, symptoms or abilities requires a good understanding of what numbers the game uses. If you are very new, I would suggest you to reuse existing traits and only slightly change them enough to become unique, and look at what the numbers are. The best way to test all of this is to play your own scenario, not guess.

Traits should have vastly different values and effects, it is completely normal and also advised to have some traits that can get leveled (e.g. Water 1, Water 2, etc.)
Here is an example showing how much of a statistic is gained.
(Numbers used: 1, 5, 10, 25, 50, 80)
Air, water and land transmission is based on a 0-100% increase.
Air/Water 1 increases transmission by 9, Air/water 2 increases it by 99, bioaerosol adds 20 more to both. Why does it go over 100? The reason is government actions, which I will talk about in the next section.
The starting transmission rates 1,1,1, and the enabling of them is all at 1 as well. "Enabling transmission" is basically the multiplier for it. If you have 100 sea transmission, but 0.5 enabled sea transmission, it will act as if it were 50. The same principles apply for rich.poor,hot,cold country effectiveness.

Usually, severe symptoms also add "Cure Requirement" and "Cure Inefficiency". Cure requirement increases the total amount of work needed to be done to find one. The speed of which cure is made at depends on how many "Active Research labs" are out there. Research funding 1-10 turn potential labs into active labs, the maximum amount is shown in a country's medical budget. With 10 glasses being the most and 2-3 (?) the least. Cure inefficiency decreases the speed that the cure is made at, rather then the amount needed. The earlier it is activated, the better. However, countries also produce it faster when they fear the disease more (due to severity, lethality or specific events).
It is important not to make the numbers high on your traits, as even a few could make a cure impossible to find.
If you want an example of what numbers are used officially - genetic hardening 1 has 0.1 cure innefficiency, the second level has 0.3. Genetic reshuffles all have 0.25 increases to cure requirement.

When giving traits prices, absolutely keep in mind! Any time a disease is evolved, the whole section where it was bought becomes more expensive, adding 1 more DNA point to costs. Symptoms locked behind many prerequisites should be a lot cheaper.

Zombies and apes have their own stat called strength. Strength increases the effectiveness of the Ape's rampage and the likelyhood of winning Z com fights of a zombie. For apes it is very simple,
the only 2 upgrades to ape strength increase it by 3, which is what you should have as a base.

Zombies behave differently however, most upgrades increase severity, which is the main factor of strength. Increasing "zombie strength" itself as a statistic practically multiplies that severity, and is considered a combat advantage. Be tame with how high or low you go, zombies die out fast, so they should not be too weak.

Once the disease has been spotted, governments will try to stop it's spread with many different ways.
You may have not known, but each action actually holds out it's own effect.
In this example, only the country that had this action happen will have -1 severity, these attribute changes are separate for each country, and are added after your base stats.
Combat strength increases the fighting spirit of Z com, while the potential increases or decreases the maximum they can have.
Change to public order decides how calm/panicked the country's citizens become after the action is taken. If it drops too low, the country goes into anarchy.

The governments don't take action out of nowhere, for them to do so, certain conditions must be met..
Besides the disease being known, awareness is based on the severity and spread of your plague. Light plagues that have barely infected the country will be mostly ignored. Dangerous plagues that have the whole country infected will be their top priority.
Global awareness is based on the awareness percentage of each country in the world.

It is very easy to add a government action, but I will still leave some tips if you need them:

• Don't make it too likely, don't make it too rare (except for easter eggs).
  
• Do not make huge deductions or increases in attributes stack on each other, or else the infections will become negative or downright unfair.
  
• Be very careful with Z com strength and public order, these numbers should only grow by small amounts, otherwise your scenario might become impossible to win or lose in.
  
• Don't add too many.
  
• If you do add a whole lot of them, tweak or remove existing ones.
  
• If you're not lazy, ( :3 ) make each action pop up on the news in grey/orange text.

Congratulations on making it this far into the guide, here is the final step to creating a good scenario.

Events are actions that are triggered when conditions are met, ranging from being visual to heavily impacting gameplay and allowing further story lines to keep going. For example, "if random(0, 10) > 2 (80% chance), Global Awareness Value = 50 (half the world knows), Country Dead Percentage = 90 (90% of the country has died), Is Not Starting Country (speaks for itself..) then the outcome occurs: News Popup - "Something something name here", Bonus Global Awareness += 10 (the world will care 10% more about the disease. )

Random example:

To optimize and further adjust events, you can go into it's settings...
The "Event Counter" serves as a sort of stopwatch, going up by one each day. It's purpose is to prevent events appearing one after another. How it works - an event happens and resets the counter, and my custom event has a threshold of 12. The game will wait 12 days, fire the event and then reset the timer once more.

After doing everything else, search for numerical errors in values, see if every event and ending can be achieved and if it is not impossible or too easy. Basically, playtest your scenario thoroughly.

If you wish, you can also manually edit every country. Mainly used for futuristic scenarios where the world has grown and become more populated, by simply increasing amount of humans.
However, do not neglect the other options you are given. Medical budget (1,000 is equal to 1 glass, aka research lab.) can be further changed for some scenarios. Or maybe some countries can be considered more important by others, making it's infection more problematic.
Important! If you allow the use of any virus, take into account the most influentian differences they may have. If you have a decreased or increased population, change the ape population to fit accordingly. If more people live there, the density should be increased, etc.

Congratulations on making your scenario! I hope this guide was helpful for you or gave you inspiration.


All questions go to me!!
Big thanks to this wiki for icons and such: https://plagueinc.wiki.gg/wiki/Plague_Inc._Wiki