Designing Single-Session Adventures part 1

Part one of a four-article series on designing and running a one-shot, single-session adventure. See the end of the article for links to the rest of the series.


Unfortunately, I’ve never been to a gaming convention, but for years I have been intrigued by the early tournament adventures of the late 1970s and early 1980s.

At Origins II in 1976, several DMs ran Gary Gygax’s new science-fiction/fantasy crossover, later called S3: Expedition to the Barrier Peaks. This stand-alone adventure was a simple one-round affair, in which various gaming groups competed. A uniform scoring system allowed DMs to give each group a score (and perhaps each player—I’m not sure).

Later, Gygax expanded the scope of his idea to a series of linked adventures. At Origins IV in 1978, over the course of two days, DMs ran dozens of groups through Gygax’s new, three-part adventure, later titled G1-3: Against the Giants. The groups that did best with the first adventure in the first round got to play the subsequent adventures in the second and third rounds, either later that day or on the following day. The sequel, D1: Descent into the Depths of the Earth, was not used in a tournament, but at GenCon XI that same year, DMs ran two follow-up adventures in the series, namely D2: Shrine of the Koa-Toa and D3: Vault of the Drow. Two years later, at GenCon XIII in 1980, DMs ran players through the entirety of Gygax’s new Slaver series, including A1: Slave Pits of the Undercity, A2: Secret of the Slavers’ Stockade, A3: Assault on the Aerie of the Slave Lords, and A4: In the Dungeons of the Slave Lords. Sometime after each convention, Gygax published the adventures. Generations of gamers have rated several of these series as their favorites of all time.

An experienced DM that tries their hand at writing a single-session adventure, whether for their personal gaming group or for strangers at a convention—whether as a scored tournament or not—will quickly find that it requires a very specific design. You simply cannot plan it in the same way that you would a long-term campaign or even a stand-alone adventure that will take many gaming sessions. What are the required differences? What tips can we use to produce successful single-session adventures? Let’s take a look. A few quick notes before we begin:

First, this brief article does not attempt to explain the game to newcomers. Also, the tips hereafter omit the painfully obvious—those cliché tips that fill so many articles—the ones on how to get along with fellow human beings. Problems usually include argumentative players, players that habitually come late, players that will not get off of their electronic devices during the game, etc. I never understood why so many articles discussed these at length, for I have been fortunate to play with a close group of friends over the past 35+ years. As an adult, I now understand the challenges that one could have while gaming with strangers, but if your group has problems with social graces and common courtesy, you need more help than this humble article can provide. The only comment I have on such issues is that they all suck up game time, which is especially problematic with single-session adventures.

Second, I apologize in advance to any authors from whom I may have gleaned the following tips. I take little to no credit for inventing what follows.

Lastly, there is no correct way to plan. I offer you here the tips and guidelines that I use to make single-session adventures.


Creating the Adventure

Choose a Design (Sandbox or Linear)

Sandbox design is a term used to describe a campaign without a set objective. Players are free to have their PCs explore as they choose. Some players love the freedom that this allows, happy to make their own objectives when they find inspiration. Other players feel frustrated and lost in such campaigns—wandering without purpose. The sandbox style of play requires a great deal of preparation by the DM, and players can drive DMs to drink by moving quickly into areas that the DM has not yet fleshed out. There are tricks to handling this, but the question before us now is whether to design your single-session adventure as a sandbox. My knee-jerk response is a hearty “NO!” as it is highly inefficient. However, a determined DM could design a very small sandbox (for example, just a few square miles, in which lie a few separate points of interest, like a haunted house, a small cave system, and a small dungeon). With only a single session to play, both players and DM would understand that there is no way that the PCs would finish exploring all points of interest. The attraction of this design is that PCs have a choice of what site to explore. Once they choose a site, the goal would be to explore that site as thoroughly as possible. Cleaning out the dungeon, for example, might spell success.

In contrast, a campaign with linear design requires the PCs to move from Point A to Point B to Point C, etc. While the PCs would have clear direction, many players might chafe at their lack of choice. This design style is sometimes derogatorily dubbed railroading, as the story seems to be ‘on rails,’ with players unable to veer off course. Of course, good linear design does not give the impression of railroading, and it is indeed possible to provide the players with some choice. For an extremely simple example, consider a party that must go from Point A to Point B. Rather than making just one path between them, perhaps with one encounter along that path, the DM can make two possible routes, each with a different kind of encounter. Make the paths look different and create advantages and drawbacks to each. The design is still linear (the party is still going from A to B), but players would not feel insignificant. In any case, linear design is by far the most efficient design, as the DM needs only to flesh out the areas that he will need. I usually select this style for single-session adventures. For many DMs, time to prepare is just too precious to waste. Besides, even free-spirited, strong-willed players will usually give the DM a great deal of slack in single-session adventures because they understand the time crunch of the session and the wastefulness of fleshing out areas that will not see any game play.

Select a Goal

This seems obvious, but you need a rough goal to get started. It can be very simple. With sandbox design, clearing a chosen area is often the goal. With linear design, ‘Kill the monster’, ‘find the treasure’, and ‘rescue the princess’ is more common, and while these may seem juvenile, the adventure’s goal should be simple. You can always spice it up later.

I tend to focus on a monster. After all, if the goal is not to simply kill the monster, you still need a challenging monster to guard the treasure or to hold the princess captive. Thus, I usually end up thumbing through the various monster books to find something that inspires me. Single-session adventures can be a great place to feature a less popular creature—one that you do not normally place in your campaigns.

I should note that choosing a goal for the adventure is not the same as making a plot. Experienced DMs already know this. The players will create the plot as they make choices for their PCs and try to accomplish the goal. Generally speaking, the DM mistake of ‘planning a plot’ occurs when a DM scripts out not only the ‘who, what, where, when, and why’ for certain encounters, but also EXACTLY HOW they will unfold. This violates the cardinal rule of DMing: “Let the players run their characters (for you get to run everything else).” I still recall an incident from many years ago, when a friend started to DM a solo adventure for me. My cavalier, having just set off on his quest, came to the edge of a forest. As it was late in the day, I decided to make camp, but the DM told me that I had to keep going into the dark forest. With eyebrows raised, I told him that I wished to camp outside the forest. He refused and whisked me into the forest anyway. That was the end of the game (character creation lasted longer). Thus, remember that establishing a clear goal is good, but scripting exactly how the PCs must accomplish that goal is bad.

One last thing requires mention here. Ensure that the chosen goal centers squarely on the PCs. Do not place the PCs in mere support-roles. Make them the heroes. Serving as the JV team is not fun, and the PCs do not have time to develop into main characters during a short adventure. They have only a few hours, and we all know that players can burn through an hour just buying supplies or debating strategy.

Choose a Game System

What game will you play? What version will you use? Perhaps the greatest factors in making these decisions are familiarity and convenience. This is fine. Consider these as you always would, but also consider whether the game system fits the envisioned genre. For example, a group may be very familiar with Dungeons & Dragons, but if the DM plans to run a low-fantasy, gritty, horror adventure, then the game system would actually work against him. He would find it more difficult to accomplish what he wants to do. It doesn’t mean that it cannot work, but the DM should realize that the rules would prod players to act in ways contrary to what he desires. In the above example, Call of Cthulhu may work much better than Dungeons & Dragons, assuming that it is available. Lest someone call me a hypocrite, I realize that I am the worst offender with this. My friends and I don’t have many rpgs besides D&D so I often make it work for whatever I am planning. However, many gamers are far more diversified than I am. If your group has plenty of games with which you are comfortable, consider them carefully before choosing one.

Also consider the edition of your chosen game system. As mentioned above, different rules encourage different behaviors. If you seek a desperate struggle for survival, with the PCs carefully managing supplies and avoiding unnecessary combat, then 3rd Edition D&D is not ideal. Consider using AD&D (1E) instead. Again, this assumes that you have options.

Avoid House Rules

Most DMs use house rule to some degree, which is fine and even expected. Yet, for a single-session game, you do not want a newcomer to waste time learning house rules. Decide at the onset to use standard rules. If you absolutely must change something, change only one thing so that it’s easily noted and remembered by all. Good players will have enough to handle during the game.

Choose a Campaign Setting

I waffled on whether campaign setting or environments should logically come next. I’m still not sure, but we’ll go with campaign setting. Is the adventure set in the world of Greyhawk, in the Forgotten Realms, in Krynn, or in your homebrew world? This is only important if the envisioned adventure goal (exploration, treasure, monster, or princess) is setting specific. If you want the PCs to obtain a magic item that controls draconians, then you’ll probably want to set it in Krynn. If setting does not matter, then your choice is easy. I was going to write that you could avoid making a decision altogether (after all, who cares where the adventure occurs?), but I do think that a game benefits when you add a few minor, flavorful details to bring the setting to life. Just because the adventure will be short doesn’t mean it must be bland.

Before making your final decision on setting, consider the environments that you desire for the adventure (more on that next time). Weighing these carefully may help you to make a decision on the campaign setting. For example, if you really want the PCs to explore a glacial rift, you can probably rule out the Darksun setting. Knowing your desired environments could also help you to nail down precise locations within the campaign setting. If the adventure unfolds in the world of Greyhawk, is it just outside that city or is it in the Wild Coast? Players like looking at maps, and they like to relate an adventure to what they already know. If possible, take a moment to select a precise location.

Some quick notes on homebrew worlds are probably in order here. There are advantages and disadvantages to using your own setting. If all of your players know and like your world, then placing a single-session adventure there should work well. However, just as you do not want a newcomer to waste time learning house rules, do NOT expect them to absorb many trivial details of your world. First, it will not happen to your satisfaction. Second, learning the nuances of your world will likely never be as exciting for the player as you imagine it will be. Remember—your homebrew world is your baby; the player is just passing through. Third, learning about a campaign setting takes time—a severely limited commodity during a single-session adventure. In contrast to a home-brew world, an established setting may be more familiar to all of the players, requiring little to no time to learn about it.

In the end, the most important tip regarding the campaign setting is to minimize the setting details needed for the adventure. Flavor details are good, provided that (1) PCs can miss/forget them without hampering their progress, and (2) describing them does not waste any appreciable time. Go ahead and mention that the gold pieces in the Kingdom of Furyondy are called ‘wheatsheafs,’ but do not ask players to memorize coinage charts or to know the lineage of the ruling House of Nyrond to solve a deadly riddle.


Keep an eye out for the next entry in this series, in which Michael will offer more specific advice on constructing the module!


This is the fourth of four entries in this series. The full series includes:

Designing Single-Session Adventures part 1
Designing Single-Session Adventures part 2
Prep for Single-Session Adventures
Running the Single-Session Adventure

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