|With a group this big, it's best to keep things moving fast. (Art by Madam-Marla)|
Running a game like this can be tricky. You are required to be expedient and efficient. You are working under a timetable for your players complete their mission. In some cases you might not be able to reassemble the same group for another session, so you will want to give them a satisfying resolution in one session. It's certainly do-able, and much easier if you follow these simple guidelines:
Build the adventure with a three act structure.
Build your adventure with a clear beginning, middle, and end. Have at least one memorable and impacting encounter for each of these stages. The beginning encounter should be simple and good for introducing the game mechanics to new players, the second encounter should bring the players into the story proper and raise the stakes... And the third should be the spectacular climax to the adventure. Consider switching things up between combat encounters, exploration, or social encounters for each of these sections. Even using this format each time, you will be surprised at how unique each adventure can be when you include unique scenes and types of encounters.
Find out how much time you will have to run the game and divide these acts into a rough schedule, so you know approximately when to transition to each scene. For instance, you might budget an hour of time for each of the three acts. Always give yourself a bit of leeway on this timetable, because nothing ever goes precisely according to plan. Leave thirty minutes or more of your playtime unaccounted for, so you can use that extra time to wrap things up or extend scenes that need more time.
Consider starting characters in media rez, or in the middle of an adventure in progress. Let them learn the ropes by starting out in the heat of battle against a nefarious foe, or during a frantic chase scene. This helps get the players involved in the game immediately, and smooths over the possibility of a rocky start.
Keep it linear.
This doesn't mean to keep it boring. In an earlier entry I have provided notes to help with running games that don't diverge much from a particular script. What I'm saying here is that you need to keep things from getting off course and taking a lot of time. Let the players do what they want, but direct the action back towards the conclusion. Your players don't have a lot of time to wander like you would in a full campaign, so you need to do your best to keep things on point.
Explain the rules once and keep it moving.
You might have players at the table from a wide range of experience levels. You probably won't have time to run through a complete explanation of the game rules before you begin. So instead, teach as the game progresses. Consider the first scene a tutorial level for those who might not be as familiar with the system. The first time something happens in the game, always explain how the game mechanic works in a clear, concise manner. Also let the players know what their options are when they are ready to take action. A little friendly coaching with rookie players can go a long way. There's no need to rush anyone, either... if a player is unsure what to do next, offer to let them hold their turn until later, and let another player take an action. This gives the first player more time to carefully consider their move without holding up the game.
Don't spend time quibbling over the rules during a one shot. Keep the game simple and swift, and avoid wasting valuable time flipping through books. Keep the game lean and mean, with a strong focus on getting things done rather than getting all the rules correct. You want the players to have a sense of progress and accomplishment when your adventure concludes. If the group has a good time, they may very well be interested in a more detailed ongoing campaign, and then you can really cut loose with some more elaborate plans and encounters.
I hope these techniques will be of use in running your own one shot tabletop scenarios, thanks for reading and happy ventures!