There is no specific requirements for how you setup for your fake news manifesto, but I recommend a manifesto that corresponds to one of the starting combo achievements. There is already a guide to these achievements on Steam, there are several to choose from.

For example: Making "Heat" Waves (Convince the world there is no environment crisis)

Starting Location: USA
Type of Fake News: Climate
Started by: Big Business
Motive: Financial Gains
Blame: Scientists

At the start of the scenario, go to the growth tab and Immediately get

- Word of Mouth,
- Internet, and
- Memes.

You will shortly see a lot of DNA bubbles pop up, as you accumulate more DNA points, get

- Bot Network 1,
- Bot Network 2, and
- Viral Chat Messages

Follow-up with

- Influencers, and
- Out of Context.

As soon as you can afford it, get

- TV Targeting,
- Talk Show,
- Buy a TV Network, and
- Buy a Newspaper.

From here onwards, keep evolving plausibility traits.... but pay attention to how many people you have deceived, when the tally reaches 800 million+ people deceived, stop and move to the adaptability tab. As you continue to accumulate DNA points, get

- Expand Victim List, and all the sequential traits that follow
- Get the three policy traits when they become available

You'll know you are on the right track when you've deceived more than 800 million people and the "cure" meter is at less than 30%.

Depending on how tight your timing with pausing the game is, you may need to do some trial and error with going back and forth between evolving plausibility traits and evolving adaptability.

I have not been able to get this strategy to work on Mega Brutal difficulty yet, although I came very close many times!

Nonetheless, you only need to beat this scenario on Brutal difficulty in order to obtain the Post-Truth Society achievement.

Enjoy!

The guide above more or less still works for Mega Brutal difficulty..... but you have to really watch your thresholds. When the number of informed people reaches slightly over 1 Billion, you have to really start juggling your DNA points between increasing plausibility vs adaptability.

- Timing is important, I suggest you slow down the speed of the game to two arrows vice three arrows so that you can pause the game as soon as you have enough DNA points for the next evolution.

- When you are picking your next adaptability trait to evolve, note that many (but not all) of them will cause a slight decrease in plausibility, this is why you have to be careful to juggle back and forth between evolving plausibility vs evolving adaptability.

- I have consistently found that once you have evolved the first Community trait, you generally don't need to evolve it any further. As long as your virality and your plausibility is high, there is little to no chance that people already deceived will become informed.

Hope this helps, enjoy!!!

From MontiTech, Thu 23 Apr 2020:
I was able too beat Mega Brutal Difficulty mode by transitioning to abilities right after buying the newspaper, and focusing on slowing the fact checking.. after buying out those. I added three plausibility. then focusing on a few of the abilities the right that do not reduce plausibility. at this point I was still well under 1 billion deceived, so as the research climbed, focus on the abilities on the right and middle; until over 1 billion deceived, then start focusing on the abilities in the top left. this returns people to unaware and they rapidly became deceived. flipping the balance to a win. I tried this a few times in a row and it seemed to work well.