A couple of years ago, then Pixar storyboard artist Emily Coats tweeted pieces of advice on making stories that she had picked up from working with Pixar, which were later compiled in several places on the internet, such as this io9 post. Later, Dino Ignacio created image macros of the individual rules which I am using in these posts.
Rule #9: “When you’re stuck, make a list of what WOULDN’T happen next. Lots of times the material to get you unstuck will show up.”
This one sounds a little confusing, but is actually pretty straightforward. The idea is that as you are compiling this list of things that wouldn’t happen, at some point something on the list will jump out at you and you’ll say to yourself “Wait, why can’t that happen? That could totally happen,” at which point you have your solution as to what to do next. The key is keeping an open mind and being willing to stretch your players’ credulity a bit.
Say the PC’s are in the middle of a street war with a rival gang, and the plot’s stuck. You set the forces up as evenly matched, and that’s resulted in a stalemate that no one, least of all the players, can see a way out of. What wouldn’t happen next? Well, the rival gang wouldn’t call for a truce because there’s too much bad blood between the gangs. But what if they did? What could motivate them to make such a move? Maybe a sudden internal power struggle, or a third party that looks even more threatening, or their resources are more strained than was previously suspected. What incentive could they offer to the players to take the truce seriously? Perhaps suspiciously generous territorial concessions, or an exchange of prisoners, or a lucrative opportunity that they can’t themselves take advantage of? If you can’t make that work, look at something else. Take stock of your assumptions about the world that have you stuck and see if any of them can’t be bent or discarded. You might have already established that the town guard stays entirely out of inter-gang warfare, but perhaps that can change if the fighting spills over into places they can’t ignore, or there’s a change of leadership.
All of that is all well and good if you’re stuck between sessions trying to figure out where to go in the next one, but you don’t have the luxury of careful contemplation if you find yourself stuck in the middle of a session. Sometimes your best option is to just come clean with your players and say “I wasn’t prepared for this and have no idea where to go. Can we end the session here and resume next time?” but if you don’t meet often or it happens early in the session that can be a big disappointment. This is a situation where D&D-style random encounter tables can actually come in handy, provided you are able to do some quick improvisation to fit it into the current situation and link it back into your game’s plot. After all, a fight that appears for no reason and has no impact on anything is pointless filler, and your players deserve better than that. Of course, those random encounter tables all involved things showing up to fight with the players, so if your game isn’t so heavily focused on combat as your average D&D game, you might just want to make your own table ahead of time. Make a list of potential conflicts, e.g. “Someone begins cutting a character down with incisive insults,” “A character is accused of picking pockets,” “A suspicious character has a fabulous business opportunity for a PC and won’t take no for an answer.” Don’t worry if you can’t see a way for a conflict to work in your game ahead of time. The idea is that when you get stuck mid-session, you can look at your list of conflicts and think “You know, that could actually work right now.”
Whatever method you use to get unstuck, you need to tie it back to an important character or object, or else find a way to make the characters involved in it more significant somehow. Otherwise, the moment your diversion is finished, you’ll be right back where you started with no way to get the plot moving again. So make that con artist an employee of the game’s antagonist, or make the insulting stranger an important figure that the PC’s will have to get help from later down the road, or ensure that important clues or links are dropped in the process of clearing up the accusations of thievery. If you do it well enough, your players won’t even know you didn’t have the whole thing planned all along.