Q: How long does a game last?
A: Convention games operate under strict time constraints. They average to be about 6-8 hours, but this varies. You may finish before time however.
Q: How do I deal with a time constraint?
A: It is important to have the adventure `short and sweet' if you wish to finish on time. There are a couple of ways to help speed the flow of the game:
Rather than role-play any character introductions, or even the beginning of the adventure, just explain it to the players (like a preamble to a book). Have them know each other, like each other, trust each other. Let each of them say a quick description of their character to introduce it.
Plan it so that it would run an hour short, since unexpected things always soon as the game begins.
Pace must me quick with simple, effective plots. Goal-problem-reward.
Q: What about rewards for the characters?
A: Even though it is a one off, most players like to receive XP at the end of a game.
You may find that because it is a one-off you let the characters become "Heroes" at an accelerated place, giving them rewards, such as items or money, much more quickly. The game should occur at a more quick-fire pace.