Recently I am in the situation where I have to start mastering some adventures to people I don't know. They can have some experience or not at all.
It's needed to end in just one session, because it's inside an event and can't be continued another day.
I didn't decided the system, but I'm trying to find one who can be explained in less than 20 minutes. Probably a simple trad game, WoD or a percentile system like CoC.
I am going to use pregenerated characters and the story will involve a little investigation and one or two combats that can optionally be solved diplomatically.
The problem is that I don't know how to calculate the time of the adventure, I see too many variables here.
Do you have any trick or system to know if an adventure is short enough to be played in just one session? (Probably like 3-4 hours)