My chance came on day two when I ran John Wick's Digging for a Dead God scenario for Call of Cthulhu. I had previously run this scenario for a group of friends who had a great time, and I felt prepared to run it in a time slot at a con. This scenario is designed for six players and I only had five in the group. Fortunately, I had considered how to run this scenario without a full player set. I was also able to substantially change many parts of the scenario using the now NPC captain as a plot device along with the other NPCs. Everyone seemed to have a great time. Here is what I learned:
Cons, for many people, are about trying new games. You also have a chance to get more people to enjoy a system or game you realy like. You never know if that will help expand a player base and help you find more players for the future. Four of my five players were unfamiliar with Call of Cthulhu. Since it is an easy system to learn, I was able to teach the basics within a couple minutes.
2. Bring Pre-generated Characters.
This lesson should be pretty obvious unless you are playing a very rules light system like Fiasco or Dread where character creation takes only a few minutes and is part of playing the game itself. People want to play and tell stories, not spend an hour creating a character for one adventure. I played in a game at GenCon where we wasted the first hour or more creating characters and never finished the game. It made me reconsider a system I may have bought into with a better con experience.
3. Do Not Railroad the Players.
The Call of Cthulhu scenario involved a group of Nazis essentially isolated in a jungle searching for a diamond mine. The scenario has only two events that must happen for it to be fun. One is a way to start the story (and could be changed) and the other is what leads to a lot of fun/terror/suspicion in the scenario. As much you may be tempted to guide the players along a story for your one-shot, they'll get a lot more out of being able to explore their sandbox and develop their own story. This obviously goes for most games, but it's especially important when they only get one shot at it.
4. When a player cannot make a decision, offer a number of options, you may be surprised.
At different times one or two players would be somewhat at a loss of what to do. They had clearly not played a lot of RPGs in the past and it was my job as GM to help them have fun. Early on I asked questions about what they were doing and offered four or so options. By the time we were done, all the players were making very interesting decisions consistent with what their character would instead of what they would do based on meta-knowledge of the game. I was very impressed. Think of it as starting with multiple choice questions to ease your players into an essay test.
I have a number of NPCs, events, objects, etc. that help move the action forward in case things start getting slow. Fortunately this was not really an issue for this event, but I have seen GM's simply sit silently with no idea how to move forward. You only get one shot with this group of players so make sure every scene adds something fun and exciting to the story!
6. Keep the Players Engaged.
Sometimes the characters split up. Do not focus too much on one group. Often I spend just a couple minutes at a time with each group, switching at a critical point in the action as a cliff hanger. This technique keeps interest at a high level and demonstrates the GMs interest in all aspects of the story and all players at the table. Sadly, I have too often seen GMs spend a lot of time with the characters they like the most, ignoring parts of the table. Follow Harlan Ellison's advice on writing when running a game: always quit a scene when you want to focus on it most - you'll always come back to it excited.
I used a scenario I was familiar with and ran before. My players enjoyed the scenario a lot, so I was confident in the fun factor this scenario could present. I was somewhat worried what types of players would show up, but other than a little play acting at the beginning by one of the players, I set the tone for the game and the players followed. I also prepared a way for me to deliver certain information to certain characters without others knowing. I prepared about 20 or so different messages, mostly one sentence, for each character. At various appropriate times, I handed the slips of paper to the player. I also use dummies to keep suspicion up. In order to allow characters to speak and plan without others knowing, I provide slips of paper for them to write on instead of needing to leave the table. The players can also use these to communicate with me. A one-shot, especially a con game, is a great opportunity for really fun PvP action with real consequences.
8. Be Ready to Improvise.
Since I knew the scenario very well, I was able to change up a lot of the events and objects to help enhance how the characters/players were approaching the game. This lesson also applies to rules. If you cannot remember a rule, don't spend time looking it up. Instead, make a ruling in your head without telling the players and go with it. This strategy will work 99% of the time and keep the players immersed in the game.
For a look at a geeklist I made about what I played, ran and won at this fall's Hoopla, click here.