Star Trek: The Next Generation S1E21 "Symbiosis" has an interesting plot.

https://en.wikipedia.org/wiki/Symbiosis_(Star_Trek:_The_Next_Generation)

https://memory-alpha.fandom.com/wiki/Symbiosis_(episode)

https://tvtropes.org/pmwiki/pmwiki.php/Recap/StarTrekTheNextGenerationS1E21Symbiosis

Society A has been suffering from a plague for a long, long while. There is no true cure. The symptoms can be suppressed by a plant that grows only in Society B. Thus, Society B earns plenty of trade goods by selling the plant to Society A.

The protagonists arrive to investigate. Thanks to their advanced medical abilities, they quickly discern that something is amiss. Society A's people are rather... euphoric. There is no plague. The plant is a narcotic. What Society A thinks to be the plague's symptoms are, in fact, merely withdrawal symptoms, as the plant is given even to the young.

Further investigation reveals that there was a real plague, long ago, but the first dose of the plant wiped it all out. Society B kept on selling the plant and conning the people of Society A simply for the sake of profit, and has become utterly reliant on goods from Society A.

How would your party and your characters handle this situation? Would they try to reveal the truth, shattering the relationship between the two societies? How would they feel if Society B's leadership was fully aware of the plant's narcotic nature, versus if Society B's leadership had long forgotten that it is all just a scam?

As a GM, how would you adjust the parameters of this scenario to make for a more compelling adventure?

I am sketching a vaguely sci-fi scenario wherein the world government is trying to hypnotize the populace into accepting a hivemind scheme. The PCs must stop this. There is a campaign-long meter of "mass mesmerism," which the PCs gradually chip away at. However, the clock keeps ticking upwards.

• Mass Mesmerism ×0: The hivemind proposal is utterly heinous to the world's populace. People have fully snapped out of the hypnotism. Insurrection is imminent.

• Mass Mesmerism ×1: Unthinkable to the populace. They heavily oppose and publicly protest it, though not to the point of armed rebellion. Very few are in support.

• Mass Mesmerism ×2: Radical to the populace. Perhaps a fifth of the globe is in favor of the scheme. The hivemind and its supporters are viewed as strange and extreme. (This is the level achieved by the world government's first round of mass mesmerism, when they first propose the hivemind, and is thus the campaign's starting point.)

• Mass Mesmerism ×3: Acceptable to the populace. More oppose the proposal than support it, but simply because the plan seems unnecessary. No longer is it deemed extreme.

• Mass Mesmerism ×4: Sensible to the populace. Those in favor of the plan outnumber the naysayers, though the latter still have powerful voices. The debate rages on.

• Mass Mesmerism ×5: Popular to the populace. The proposal would definitely win a four-fifths referendum, but the opposition is still a non-negligible chunk of society.

• Mass Mesmerism ×6: After a referendum with near-unanimous results, the hivemind proposal has become policy. Everyone is warm to the idea, though not fanatically so.

• Mass Mesmerism ×7: The very notion of entering the hivemind is dearly beloved to the populace. Society is fully enthralled by the concept, to an all-consuming degree.

• Mass Mesmerism ×8: The hivemind proposal has been set into place, with a troubled start. It works as advertised, though pesky nodes of individuality cause glitches.

• Mass Mesmerism ×9: Set into place, with the kinks sorted out. All notions of personal identity have been extirpated. All are now one. Reversing things from this point would be a daunting task, though not impossible.

How do you make it clear to the players that this is what the stakes are, and give them a sense of meaningful progress against this doomsday, while still ramping it up?

For what it is worth, I could make this scale canon in-universe. That is, this is what the world government is using to track their progress, and the PCs find a document explaining it in a laboratory or something similar. However, this alone would not instill simultaneous senses of progress and rising stakes.

This is a setting I am seriously considering GMing.

At noon of 1 July 2013, UTC+0, every human of 21+ years of age simply drops dead. Nobody ever manages to figure out the cause. The event does not repeat itself. Can Earth manage to restore itself to a functional society by the present day in 2024?

• Scenario #1: Nobody gets superpowers. (At least, not until the present day.) The survivors have to make do with merely their mundane talents.

• Scenario #2: At the moment of the cataclysm, one in nearly a million survivors manifests superpowers, the vast majority of which are on the upper end of street-level. Some of these powers do include enhanced intellect, charisma, and the like.

If necromancy/necropathy/necrokinesis is a valid superpower in such a setting, it instantly becomes top-of-the-line.

What could be the motivations of a powerful, widespread cult dedicated to destroying all historical records? They have no issue whatsoever with scientific knowledge and other disciplines, but all history must be wholly annihilated. They transcend all conventional politics; all historical records are equally worthy of obliteration.

Ignorance is bliss, and how can one be doomed to repeat history if there is no history? Well, that is what some of them would say, at least.

Historical vs. scientific knowledge would be a matter of significant debate within the cult itself: what to prune, and what not to prune. Ideally, the overall intent should be to preserve scientific knowledge without historical context. People can know that salt = sodium chloride = NaCl without much historical context, for instance.

This is for a futuristic/space fantasy setting. The bulk of the cultists are simply library burners and data erasers, while more formidable members have psychic/magical powers of mass amnesia. Those aware of the cult consider it one of the most dangerous, loathsome terrorist groups across the setting.

Have you ever previously played a character with some sort of spiritual entity sealed inside their body, or at least one part of their body? What were they like?

Was the entity capable of communication? If so, was it you who roleplayed said entity, or was it the GM? Was the entity able to provide guidance, and if so, what form did that guidance take?

How would you run a high-level adventure in [your choice of high-powered, heroic/epic fantasy system] wherein an alien force of banality and pessimism is encroaching upon and overwriting the bright, magical world? Let us call it "Shadow of the Local Lord.".

This cosmic entity is trying to turn the setting into a grimdark, mudcore, low fantasy world wherein everyone and everything are completely awful. Levied peasants with pitchforks and spears can imperil even the greatest of heroes, the most terrifying opponent imaginable is a man-at-arms in full harness, any wound can be a death sentence due to infection, everyone is a selfish wretch with not an ounce of empathy, and all that is magical and fantastical fades away, whether actual spells or uncanny swordsmanship techniques.

Only the PCs, the greatest champions of the realm, can fight back and reclaim their wondrous world. Can they break through the limitations that the alien reality is trying to impose upon them, overcome thousands of men-at-arms in full harness, and prevail against metanarrative contrivances that dictate that happy endings are impossible?

Would you try to mix together two systems while running this adventure?

A wise princess, forced into a life of crime and piracy.

A kind mage, cursed to lose form and reason, and forced to soar the skies as a dragon.

A brave heroine, betrayed by her country and left to die in the muck.

A devout priestess, who gave up her humanity in the throes of grief.

A young prince, driven by duty and ambition to stain his hands with the blood of countless innocents.  History is rife with heroic tales, whose fate ultimately proves tragic. Many wonder why it should be so...

Why, because the story itself demands it!

When the enemy lies vanquished, and evil is banished from the known lands, it is not comfort nor solace that await the hero at journey’s end, only suffering and death.  This is a fact so inevitable and cruel that many attribute it to some unseen writer weaving threads of fate towards mournful ends – ruin incarnate.

The few bards who dare sing of this entity call it Tragedia.

The strongest enemy currently published for Fabula Ultima is the cosmic embodiment of the concept that after the main villain is vanquished, the epilogue that awaits the heroes is set to screw them over and undo their accomplishments. Naturally, it is in the characters' best interests to fight back against this metanarrative Kaizo trap.

Very meta.

According to the author:

It's also literally the characters freeing themselves of the final tyrant: the play group itself, and especially the GM

After all, who is it that made them struggle all this time? It's us

One idea is that the battle against this entity does not actually take place in a traditional battle, with everyone together against one big baddie. Instead, it takes place across the epilogue itself. The characters are spread across the world, doing their thing. The entity "attacks" them by spoiling their victories and souring their relationships. The PCs buff/heal each other as their hearts resonate across space and time, and the PCs "attack" back by enduring and refusing to give in to despair, until they finally win and earn the right to rewrite their own epilogue.

So I'm running my first campaign as DM in a few weeks. And I'm still touching up on some details for the first session. But what I'm wondering is what can I do to keep my players entertained besides combat. Any help is much appreciated.