A campaign’s ending should conclude the last of the major conflicts and tie up most of the threads of its beginning and middle. (It’s OK to leave some loose ends for characters to explore in the next campaign.) You don’t have to take a campaign all the way to level 20 for it to be satisfying; wrap up the campaign whenever the story reaches its natural conclusion.
Allow time near the end of your campaign for the characters to finish up any personal goals. Their stories need to end in a satisfying way, just as the campaign story does. Ideally, some of the characters’ individual goals will be fulfilled by the final adventure. Give characters with unfinished goals a chance to finish them before the very end.
Once your campaign has ended, a new one can begin. If you intend to run a new campaign for the same group of players in the same setting, using their previous characters’ actions as the basis for legends is one way to invest your players in the new campaign. Let the new characters experience how the world has changed because of the actions or accomplishments of the previous campaign’s characters. In the end, though, the new campaign is a new story with new protagonists. They shouldn’t have to share the spotlight with the heroes of days gone by.
Sometimes you run out of ideas for your campaign, or it gets so sidetracked that you have no idea how to bring it to a satisfying conclusion. You might just not feel excited about it anymore, or you might be so excited with ideas for a new campaign that you can’t focus on the current one. Any of these might signal the end of your campaign.
The best way forward when you want to end a campaign is to talk to your players about it. If you’re not excited about the game anymore, it’s quite possible they’re not either, and you can change or end the campaign to everyone’s satisfaction. Consider the following possibilities:
Player Input. If you’re running out of ideas for your campaign, your players might be more than happy to supply you with some. Find out what they’d like to have happen if the campaign continues. They might give you all the inspiration you need!
Switch DMs. One of your players might have so many ideas about the future of the campaign that they’re willing to take over as the DM. You can either take over that player’s character or make a new one of your own. Let go of your plans for where the story was going, and allow the new DM to have creative control.
Transport the Characters. If you or another DM wants to start up a campaign in a new setting but the players don’t want to make new characters, consider having the characters travel through a portal to a new world.
Arrange a Grand Finale. Sometimes an end to the campaign is the right answer. Look for ways to end the campaign with a bang, even if it’s earlier than you originally planned. Flip through your campaign journal to see if there are forgotten elements you can resurface for one last hurrah.