Should you forewarn your players of campaign endings or should you keep them a surprise?

It’s never occurred to me not to forewarn my players when the end of a campaign is imminent, even if it’s just a quick announcement at the beginning of the session. I’d always felt that it gave the characters a chance to pull out all the stops for a glorious finale and give the players a chance to wrap up dangling threads or accomplish something they’d wanted to do before the campaign ended. It just seemed like a good plan.

Still, there are times when I wonder if it wouldn’t be fun to keep the players in the dark until the curtain fell. Why should they approach the final conflict any differently than the previous ones? Why should a PC suddenly feel the urge to sacrifice herself for her friends in the final battle, when she never would have if she knew further adventures awaited? Why should a player have foreknowledge of the end when spending the last of his XP?

The answer is obvious; most of the time we’re looking for a dramatic finale, and things like heroic sacrifice and throwing everything one has at a final enemy makes for a thrilling conclusion. One can make the argument that, on a meta level, knowing that the campaign is marching forward encourages players to make conservative decisions and a finale frees them to play their characters as they should have been all along.

That said one can also make an argument in the other direction. If the characters have been playing a certain way all along then it’s ‘in character’ to expect them to do so for the final encounter. Keeping the ending secret preserves that play style; they win or lose based on how they’ve been playing all along.

As with most things, there’s also a ‘third way,’ and that’s to let the players know up front when a campaign is expected to end. Players tend to make different choices when they know a campaign is going to end after six adventures rather than ‘play until we tire of it.’ Even in this case, however, one can make the argument that foreknowledge won’t stop a character from behaving differently in Adventure #2 than in Adventure #6.

As I said from the outset, this is purely theoretical to me, so I’d be very interested to hear from you! Have you ever run a campaign where you didn’t tell the players that it was ending after a particular encounter? How did they react? Would you do it again? If you normally tell your players about endings, would you ever consider a ‘stealth’ ending? Would the campaign/genre matter?