The Apocalypse!

[New Earth Man]

So my campaign world was shaped and formed by an event that happened roughly 4,000 years ago in the timeline known simply as 'The Cataclysm.' no one knows what really caused it but a lot of the creatures of a magical and aberrant nature are a result of that event. Entire land masses were changed by it and magical strangeness still exist because of it. This event pretty much resulted in the apocalypse and the world my players romp around in now is basically a world rebuilt after the fall.

Now recently, the players have got it in their head that they would like to go back really far and play a campaign that take them from just before the Cataclysm to just after so they can try to live through the apocalypse and see the one pivotal event that shaped their world.

Now my question is, has anyone ever tried to do anything like this and if so, how would you do it? What sort of adventures could there be? What encounters and challenges? What level do you think I should start them at? I'm basically looking for advice on running a campaign in which the characters will be one of only a few hundred thousand left alive. It will be dark and hideous and they will witness the world descending into madness.

Some background: The Cataclysm was caused by the arrival of a sort of cosmic evil that roams the universe seeking worlds filled with life. It then proceeds to sink its greasy tendrils into the heart of these worlds and drinks deep. It also happens to plant psychic sleeper agents among the populace so that when it puts out its 'call' they hear it and begin to enact its will. These poor individuals become everything from raving lunatics to powerful cult leaders with armies of slavering aberrations and the like at their command.

[Dox of the ParaDox twins]

I once ran a fallout based game from level one to twelve. It was really fun having to survive and fight normal monsters twisted by the radiation. I would recommend working on the mood more than anything else.

[Cuup]

Is your plan to have the threat looming, and have the PC's try to stop it, or are they simply meant to witness the event with no hope of stopping it?

I ran a game where the PC's were messing with time. They needed to go back and undo a terrible military defeat that basically left the Orcs the victors in their ceaseless war against Humans. Messing with time isn't taken lightly, and Angels (among other creatures) actually descended to stop the PC's from using the "time machine". In the end, they won after defeating many high ranking Angels, undid the military defeat, and saved the day. Some beings aren't tethered to time like mortals, though, and Gabriel, Archangel and herald of a deity of Law (Angels could be LN in this game) descended with his greater artifact weapon - The Eraser Blade - and deemed the time meddling an abomination, and concluded that mortals weren't deserving of his master's gifts. With his deific sword, he rent the Law alignment from the Material plane.

The next campaign I ran took place about a century later, where Chaos was the dominant alignment. Civilization was clinging on by a thread, portals from the Chaotic planes (particularly the Abyss) popped into existence on a regular basis, while summoning anything from a Lawful plane was extremely difficult, and magic became more and more unstable the closer anyone got to the epicenter of the cataclysmic event (where Gabriel rent Law from the world).

The PC's from the first campaign died with the event, so I didn't have them witness it and try to survive afterwards. Something that might be fun for your campaign though - especially since the Players know that there's an apocalypse coming, even if their characters don't - is to have the first part of the campaign be about trying to prevent the end coming, only to have them discover that cancelling one apocalypse only triggered a second, even worse one. It could be a cool misdirection for anyone who goes into it believing that their mission is ultimately impossible, knowing that they've already played a game set in the future where the apocalypse already happened.

[New Earth Man]

I plan on it happening no matter what - the only person that can stop this thing hasn't been born yet and is born just before it happens again and manages to stop it on the second go around. But I figure this story will be more about survival and saving what can be saved. I think I'm looking for a sort of what if story about what would happen should the Great Old Ones from the Cthulhu Mythos were to wake up and start their reign. Entire races were twisted by this event and one entire race even managed to open up a gate and got thousands of people through before the end. Mostly, the story will follow the dwarves - there were no humans on the world at the time - so most players will have dwarven characters if that helps at all.