If you are thinking big, creating a campaign around a plot twist can be the biggest challenge of all. One way to do this is to create a Turbulent Change campaign.
The premise of this type of campaign is that after a couple of sessions to establish a baseline, you abruptly place the players in the middle of an extreme event that upends their normal. There are a few devices that work well:
Civil War: There is a sudden uprising that splits local loyalties, destroys the established order and requires the characters and NPCs to pick sides.
Allowing a few friends and allies to become ideological foes can provide good RP and plot material.
Exile: An event causes the party to be exiled from their home suddenly and dramatically. A few contacts will remain supportive, others will believe the party deserve their fate and will no longer support them.
Assets and belongings could be taken and family members disappear. Your party will need a new home, possibly in a very different culture. The campaign arc may eventually allow them to return.
Natural Disaster: The unexpected need not be malign in nature.
Fire or flood can completely change a character's fortunes, wealth and home circumstances. Avalanche or landslide can cut off a location from its established trade routes meaning their wealth, food or protection is abruptly severed.
Overcoming this, surviving hardship and forging a new future can be a rewarding campaign arc.
The Antagonist Strikes: Instead of gathering power and mustering forces over time, an antagonist acts suddenly and decisively early in the campaign.
The party cannot prevent these events, nor can they save everyone they might wish to. The campaign arc will revolve around avenging and correcting this sudden reversal of fortune.
Happy Gaming!
-Stolph (Ed)
