TheCosmicKid
Hero
They don't have to know when the deadline is. In fact, it may be better if they don't. The uncertainty means every rest is a risk, rather than a calculation like "Well, it's four hours until midnight, so we can short-rest three times." Also, verisimilitude: the fog of war and all that. And it incentivizes active intelligence gathering: maybe, if they play it smart, they do get the timetable and can plan around it.(1) You have to somehow convey the status of that offscreen, in-game clock to the players at all times, perhaps through e.g. a magic item that lets them spy on the cultists, or a defector from the cultists who lets them know what the calendar schedule for sacrifices is like...
What was going to be a climax becomes a cliffhanger. That sort of pivot is a pretty handy tool in the DM's bag of tricks.(2) You have to align gameplay to the in-game clock, but that doesn't make your metagame time constraints disappear, and now you have to satisfy TWO sets of constraints instead of one. If the evening ends, but there is still time on the in-game clock remaining, you have to delay resolution of the story until the in-game clock runs out EVEN THOUGH THAT CLOCK WAS ARBITRARILY DERIVED IN THE FIRST PLACE. You're spending the evening without a climax or a clear win/lose condition, and you're doing it for no particular reason.
Yeah, that doesn't happen with my group. It's been almost eight weeks now since we last played, and my players would slit my throat if I suggested not resolving what happens to their intrepid heroes currently fleeing through the jungle from enraged snakemen. Like I said, make it a cliffhanger. Then it'll be worth the wait. Fans wait years to see what happens next in the Star Wars movies.Depending upon how often you game with this particular group, and how busy your various lives are, that might potentially mean that you NEVER get closure on this particular adventure--next time you find time to get together, everyone may want to play different characters entirely instead of resuming the interrupted story arc from eight weeks ago.
My group would be irked by the notion that they lost because a random encounter wasted thirty real-life minutes even though it was at most thirty seconds of in-game time.Precisely. In the absence of a compelling in-game reason to prefer a particular timeframe, why not simply align the failure condition to the metagame constraints so that you NEVER have to "wait until the next session... to see what happens?" Why not just make "ran out of time" the same thing as "you lose this time"?
I can understand that.It's not appropriate for all adventures, but I see definite potential for using it in certain kinds of episodic adventures, especially with new players and busy players. Especially busy, new players who have five kids under the age of ten, for whom scheduling even a single game session can sometimes take six weeks.