The art of the one-shot can be complex, but it can also be simplified. To design a campaign requires different skills altogether--while a campaign required sustained, connected effort, a one-shot requires focus and a different kind of perspective. In the past, I've addressed specific needs for one-shots: how to write a one-shot about a murder mystery, for instance, or how to write a one-shot based on a movie. But thinking about a general one-shot is important, too, so let's consider the steps to take when writing a one-shot for a general purpose.
[Remember to check the top of the homepage for a catalog of one-shots based on movies, original systems, and D&D.]
In this guide, I'm going to provide two approaches to developing a one-shot: one for planner GMs and one for improv GMs. They're functionally very similar, but the level and type of preparation is different. Both follow the same basic formula:
opening scene + intermediate step + escalating incident + intermediate step + finale
Let's address the formula first, and then we'll get into how to develop the parts of it. The opening scene establishes the one-shot's stakes and setting. It's here that you'll deliver the quest, so to speak, that will define the one-shot. Because of the nature of a one-shot (it's contained and short), you'll really only be concerned with one primary goal, and this is the quest. You should also spend some time developing the setting by describing the environment, the NPCs, and the other things that may be relevant. By the end of the opening scene, the players will be on their way.
Then, there will be an intermediate step. For planner GMs, this will mean establishing a small step between the beginning and the escalating incident. This could be a complication or a distraction, or perhaps some time for characterizing the player characters. For improv GMs, this will be an exploration sequence. The players will be allowed to freely investigate and interact with the world while they move forward in their quest. For combat-oriented one-shots, this is often a small-scale fight.
Next is the escalating incident. This is the midpoint in the story, and it will raise the stakes of the adventure. There are several ways to do this: you can give the players a glimpse of their foe, perhaps in a short fight which doesn't end in the foe's death; you can reveal that someone is working against them, and they are now racing the clock to succeed; you may add an obstacle that complicates their progress. The vital thing here is that the story pick up momentum as it heads into its second half. For combat games, this should be a major battle.
Then, there is another intermediate step. For planner GMs, this will be another complication or distraction, or more characterizing time if your players wish. The complications shouldn't rise above the level of the escalating incident, but you can make things more dire and frustrating. For improv GMs, this can be more exploration, especially to see what the players do about more threats to their success. For combat games, another small-scale fight.
Finally, we move into the finale. In the finale, you resolve the story and try to offer a dramatic conclusion. For planner GMs, you will want to devise consequences for a few of the overarching ways that the one-shot might end. For improv GMs, you'll be focusing on offering a satisfying ending off the top of your head. For combat games, this is the big battle with the big bad that everything has been building towards. There should be some meaningful challenge overcome here.
This is how the formula works: introduce the tension of the opening scene, lessen it slightly with the intermediate step, heighten it again with the escalating incident, lessen it slightly again (but still at a higher level than the last intermediate step), and bring it to a head with the finale. This up and down effect with the momentum keeps things dynamic and allows the players to really get into the story with the allowance of some breathing room. So let's talk about how to write these parts of the formula.
1. Opening Scene
Start with the quest. What is this adventure about? You need a hook or a concept to begin with. Look for inspiration and try to determine what the most distilled experience you're going for is. If it's a combat game, what do you want the players to get out of the fights? If it's a roleplay game, what do you want the players to emotionally experience? If it's a shenanigans game, where do the laughs come from? Once you know the central element in your game, it's time to really get started.
With your idea in mind, how do you present it as a story? If you have combat in mind, who is the enemy, and why is fighting them important? If it's a storytelling one-shot, what are the key scenes in the story? If you're playing for hijinks, what story will accommodate your laughs? Keep in mind that this doesn't have to be original or elegant. If you want to do a one-shot about evil lemonade that makes people into zombies, you don't need to reinvent storytelling to do it. What kind of story would easily be a home for that? A classic zombie story with the twist of the evil lemonade would serve perfectly well. Feel free to keep things simple in a one-shot--there just isn't time to really get carried away with the details.
That said, there are details you need to prepare for, no matter how much you improvise. The setting is contained within the opening scene, and it's important to spend some time thinking about this in advance. How does the setting affect the story? How does the story affect the setting? With the evil zombie-causing lemonade example, if the outbreak has been going for a while, the setting will feature destroyed or abandoned buildings and lots of danger, whereas if the outbreak happens during the opening scene, the setting should be more normal. The way NPCs think, speak, and act should be changed by things like this.
But even beyond this conceptual information, you need to know about the places in the one-shot. You don't need full detailed maps of everything, but you should know the layout of the areas, what is in them, and how the area functions both logistically and socially. These details come up in-game incredibly quickly, and establishing the setting means being able to furnish information about the world with little time. Even good improv doesn't match good preparation, so be familiar with the spatial details of your one-shot before you get going.
The actual offering of the quest itself is also important. I cannot tell you how many times I have offered the quest in a one-shot and had resistance from the players over accepting it. This is partially due to the fact that I have played with a lot of shenanigans-type gamers, and they tend to be the ones who resist a fairly offered quest. But we cannot assume as GMs that the party will accept the quest. In the confined context of a one-shot, the quest is basically everything. So either offer a reward so sweet that the party would be fools to turn it down (and don't just go for lots of money--really offer something that you know your party in particular would want), or announce a hefty penalty for not complying (death can be a good option here). You could do both if so inclined. But the quest offer must be clearly considered beforehand, because the one-shot cannot start in earnest until it is accepted. (Note: if you are instead opting for a rescue mission, make sure to be very clear about how important kidnapped NPC is to the party.)
With the concept defined, the quest written, and the setting considered, the actual playing out of the opening scene is fairly simple. To be honest, I find this part of a one-shot quite boring. We all know that the one-shot requires compliance with the quest, but there are so many logistical details to attend to (the ones named above). Nevertheless, you shouldn't speed through the opening scene. Deliver the information, get the quest started, and get the party on their way so the one-shot can truly begin.
2. Intermediate Step
There are a few approaches to the intermediate step. You can keep things thematically consistent and introduce a side element of the quest's story here. You might also choose to present your world as larger than the story and throw in a moment that is consistent with the tone of the story but involves separate dramatic stakes. Let's consider the benefits and drawbacks of both of these approaches.
Keeping things thematically consistent is attractive for fairly obvious reasons: you get to keep your one-shot consistent narratively and tell a deeper story by saying more about the main story you have chosen to focus on. Let's imagine this using the evil zombie lemonade example. In the opening scene, you establish that evil lemonade caused an outbreak, and the party must follow certain steps to end the outbreak or cure people or both or establish a safe place to live away from the zombies. So in the consistent story, you present a small piece of information about the outbreak. You could reveal a lab where the evil lemonade was developed; you might have a person who is transforming into a zombie in front of the players; you could encounter a store which is totally ransacked except for dozens of bottles of evil lemonade. These keep the players' attention on the overall story.
On the other hand, a scene with separate dramatic stakes can expand the scope of the one-shot. Rather than sticking with only zombie-related scenes, you could include a slice of life that steps outside of the overall story. So as the GM, you might have the players stumble on a family that doesn't seem to have noticed the outbreak. You could have a bandit raid happen on the settlement where the one-shot is set, only for the bandits to realize there's really no plunder to be had. You might even have a meteorite crash down just beyond the city--to respect the one-shot's story, that meteor shouldn't have many larger story implications, but the sense of impending doom would contribute to the atmosphere of the story.
For planner GMs, these intermediate steps are things that should be planned out in less meticulous detail than the opening scene, the escalating incident, and the finale. Even if you aren't an improv GM, you should allow your players at least a bit of freedom here. Without a bit of reined freedom, the players will feel like the entire one-shot is already decided, and many players will lose interest. So I suggest writing a simple framework and filling in the spaces in between as the players explore. They don't need complete freedom, but just enough to explore a space and talk to someone in-game is good enough to keep the game moving while giving them a sense that the story includes them.
For improv GMs, these intermediate steps are spaces to finesse the direction of the story. In the first intermediate step, you can help to make sure that the party follows the quest well enough. If they're hesitant in this step, offer them some incentive to continue (increased threats of danger can work) or show them the dramatic stakes in another way (the way the scene suggestions above demonstrate the direness of the situation). You want to guide the momentum of this section just slightly down from the excitement of the opening scene and then rise into the escalating incident.
For combat games, these fights should be short and somewhat simple. I would recommend making the fights in the intermediate steps be about half the length and difficulty of the fights in the other sections. The goal here is not to overwhelm the party; we want to challenge the party a bit, but these moments are not the star of the show. The more substantial fights surrounding them should be the star here.
3. Escalating Incident
The escalating incident is where we raise the stakes, and so it should be something that intensifies the need to complete the quest or a complication that requires the party to complete the quest in a specific way. One strategy here is to allow the party to pursue an easy and simple strategy for the quest in the first two parts of the one-shot and then reveal in the escalating incident that something has occurred which renders that plan useless. (An antidote to the zombie lemonade has been proven to kill the patient the following day.) Alternatively, you can just apply more pressure. In combat games, this is where the big bad hires more foot soldiers or takes on a stronger form (or something to that effect).
For planner GMs, this scene is relatively simple. You need to get your party from the previous intermediate step to the next, and you need to show a way that things have gotten more dire. This should be as simple as creating a transition from the previous intermediate step, developing the escalating incident itself, and creating another transition to the next intermediate step. Be sure that if you have an NPC appear in this part of the one-shot who you want to appear in the finale, you have taken precautions to make sure that they survive this scene.
For improv GMs, the escalating incident can be delicate. You want to up the stakes, but still leave room for the finale to be the star of the show. You need to create a memorable scene that anchors the middle of the one-shot, but you can't steal the show in the middle scene and disappoint in the end. I recommend just a bit of planning so that you can calibrate the intensity just right, but that's really the only part of the escalating incident that's important to plan if you improvise.
It's important when actually deploying your escalating incident to use appropriate dramatic pacing. I think that having the escalating incident revolve around a surprise is a really helpful strategy. The opening scene and the intermediate incident will likely follow a traditional and familiar series of beats, and that's perfectly fine--they're serving important purposes. But the escalating incident can buck that pattern and make the one-shot more memorable. So try to go with something that really inspires the players. For our evil lemonade example, let's say that the players defeat a horde of zombies only to discover that the zombies have lemonade-inspired telepathy and can communicate across the area. This then leads to more zombies appearing during any combat. The strength of this example is in how it escalates the stakes and also pushes the players towards a shocking moment.
Once you've delivered your escalating incident, it's important to offer some indication of what the way forward is. You can make it obvious (an NPC directly tells the party how to move on, for instance) or subtle (there's a faint trail of glowing blood that leads to the next area, possibly). But a sign of what to do is pretty important. Remember that you've just confounded your players, so they'll be stuck in consideration mode until they can figure out what to do. You can offer a slight hint and get moving to the next part of the story.
4. Intermediate Step
The function here is the same as last time: connect the escalating incident to the finale and provide some variation in tone and momentum. This intermediate step should be slightly to moderately more exciting than the last one. It should also include some foreboding omen of the struggle to come in the finale. For the zombie lemonade example, this might mean a massive horde of zombies in the distance, the death of an ally, or the appearance of a more powerful type of zombie.
In general, you should follow the same steps and considerations here as before. Allow a bit more freedom than the major parts of the one-shot, slightly lessen the tension compared to the surrounding sections, and be conscious of how you are pacing things; you want a gradual dip after the escalating incident and a rise into the energy of the finale.
5. Finale
The finale is the part of the one-shot which is hardest to write. This is for a number of reasons. Firstly, a good ending allows the players to make a meaningful choice. But if they have a choice, there are infinite possible choices they could make, and no one could ever meaningfully prepare for that. So writing an ending that directly responds to players is fundamentally impossible. Secondly, that leave us with preparing an ending ahead of time, which I personally detest. But a simple binary choice isn't exactly rewarding for players. So we are left with preparing a number of likely options and having to improvise based on actual player input. But this is big picture talk; let's consider the actual details of writing and playing your finale.
In a one-shot, actually seeing the final conflict through is vital. Some players resist conflicts that make them nervous; if you have one or more of those in your group, be sure that there is some mechanism that forces the party to commit to the conflict. If you're playing a system that has magic or magic-like forces in it, you can use those rules to confine players to the conflict.
I want to add here as a disclaimer that I despise railroading. I think that taking choices away from players spoils the entire purpose of tabletop gaming. That said, one-shots are different. A one-shot is meant to be played in one setting and moved on from. But some players' natural tendencies tell them to not commit aggressively to much of anything, and allowing that as a GM would genuinely mean less enjoyment for everyone at the table, including the player who hesitates. Think about how much fun people have when games pointlessly drag on and on. Or how much fun players really have just sitting around and doing literally nothing. It pains me to say, but in the case of the one-shot, you do actually need to push your players around a bit more to be able to offer the experience they're looking for.
So, you've gotten your party into the final conflict. There are many ways to play tabletop games. Maybe your players are trying to kill a big bad; maybe they're having a charged discussion with an NPC; maybe they're cracking one-liners at their foes. Whatever energy your players give you, run with it. The end of the one-shot is the most vital place for improvising. Use your best skills to match the players and manage the pacing. Build up the energy as much as you can without exhausting or overwhelming your players, and then allow the conflict to be resolved at just the right moment. [Check out this guide on managing a boss fight for more details if you're doing combat for a finale.]
The most delicate part of the entire one-shot is the final moment. After your party has emerged victorious (or not, depending on your type of game), you need to leave them with something that resolves the one-shot. This can be prepared if you can discern what your players will do ahead of time. More than likely, though, you will need to either improvise this moment or adjust something you've pre-written. The goal of this final moment is to close up the story of the one-shot and offer a glimpse at some consequence of the party's actions.
Actually doing this is more complication than just saying as much. Let's consider for one last time the zombie lemonade example. The players discovered the zombie outbreak, made it past obstacles, discovered the problem was worse than they thought, braved even more obstacles, and fought to save humanity. How do we end this? If they did really save everyone, we paint a picture of a recovering city: destroyed buildings being rebuilt, people recovering in sick wards across the city, a ban on lemons entering city limits, families once again peaceful and safe in their homes. (For a fun twist, after this idyllic ending, we can also briefly mention a lone bottle of lemonade that went unnoticed until a young child found it, too thirsty to resist.) If they failed, we describe a ruined countryside, swarms of zombies devouring wildlife in the woods beyond town, plants overtaking the now-abandoned city. And after a while, the zombies pass on to other places, and settlers arrive in the forgotten town to forge a new life. (Again, we can twist this and add that they, unsuspecting, discover the lemonade and are grateful for a sweet drink.) You'll notice that both endings provide a tonally consistent resolution to the story, and the twists serve to make the one-shot feel like there's something more--but the adventure is over. The players are left wanting more and yet feeling satisfied at the same time. This is the ideal outcome for the finale.
These five scenes together will take most parties between an hour and a half to three hours, depending on how much combat is involved, how much players investigate the world, and how much time the group is allotting to playing. With hijinks players, things take less time; with combat players, things take more time; roleplay players are somewhere in the middle. You can add or subtract more intermediate steps if you see fit for your party's needs. If you're having a hard time getting the game to follow the momentum you want, try this guide on how to pace your game.
And while there is more to writing and GMing a one-shot than this formula, most everything else falls into place when you've done a bit of good planning and preparing for your players. Thinking of a one-shot as one continuous hours-long experience makes them seem daunting to write. But if you think of it as just being five short scenes, it's much more approachable. So give it a shot--a one-shot! (Sorry.)