A blog for practical advice, turn-key resources, tips, and examples of how to run a roleplaying game.
Let me clarify the 1 hour rule: It's one hour for every ten players for every hour of LARP. So for 10 players for 4 hours, you need 4 hours of prep. For 25 players for 4 hours, you need 10 hours of prep. Type this formula into google:PLAYERS*GAMETIME/10Replace PLAYERS with the number of players and replace GAMETIME with the length of your game (e.g. 4 if it is a 4 hour LARP). The answer it spits out should be the number of prep hours that you will probably need to produce real opportunities for dramatic action, as opposed to just "plot."
OK, so I kept my example to comments! If I plug in 24*3.5/10 I get 8.4. That's about eight and a half hours of prep for a typical (from my LARPing history anyway) 8pm-11:30pm Friday night Elysium style Changeling LARP for 24 players and a GM staff of 2. The high water mark for attendance was higher, and typical attendance was slightly lower, but you write for the LARP you want, not the LARP you're afraid you'll get. Over the course of 2 weeks between games, that 8.4 hours of prep could be...2 hours of BGA response, using those to introduce "footballs," remind players of footballs, or referee players who want to use BGAs to move footballs up the field.1.4 hours going back and forth with a player on a single BGA to help her create a 30 minute scene for the whole group. This scene should be designed to highlight the player's character's strong positions on issues for which there is conflict in the game, and hint at that character's vulnerabilities as well as strengths.2 hours to write an NPC visit that should get the attention of 10 players for 2 hours. This NPC is a vehicle to effect change on a contested issue. 10 players care about that issue, some for, some against. The NPC represents a 2-hour opportunity, and the time limit may motivate them to act despite consequences. A guest or staff member very familiar with the setting could be tapped to play this NPC. The staff/guest will need a half-page reference list of the things they need to accomplish and the challenge s/he should present to PCs trying to "move the football" on the contested issue. Additionally, I'd have to write a 1-2 page bluesheet about the NPC and the contested issue itself so the person playing the NPC had that understanding.2 hours to write an investigation scene that should get the attention of 14 players for 90 minutes. The remaining players are concerned about another issue. Some of them have done something naughty and want to cover it up, and others are investigating it. It takes place in gamespace, so all of them are present (except the ones talking to the NPC at the time). This plot requires contingency envelopes, set dressing and props, so that several clues can be seeded among the players and around the game space. The main mechanic is searching and hiding things, and actually doing it subtly so nobody notices. A GM familiar with the players' characters' magical abilities is needed to moderate those, if (when!) they get used.1 hour of collecting the props and set dressing for the investigation scene and costuming for the NPC.
All of this is in addition to writing the plot. That usually comes first. It may be a general outline or timeline structure that was written at the start of the current arc, or it could be separate outlines for each contested issue (two or three of which get brought up at this game session).Notice how this is an Elysium style LARP, and that means it's OK to have less than 3.5 hours of scheduled plot events. As it is, some players will have 2 hours of scheduled events and others will have 2.5 hours. They will use the 60-90 minutes of "free" time to react to the opportunities for dramatic action they got to play with in the scheduled scenes with politics and scheming. In effect, those "empty" time blocks should be scheduled in for an Elysium style game just as much as with actually scheduled events. Here's my game schedule based on that prep:7:00pm, GMs arrive, set up set dressing, organize props and costumes, review notes.7:30-8:00pm, Players arrive because I told them the game starts at 7-7:30.7:30-8:00, GM answers player questions until 8pm, then ejects everyone from the OOC area.8:00-8:30pm, Politics & scheming (remember, they got BGA responses that they may want to discuss)8:30-10:30pm: NPC wants to talk to [people interested in issue A]8:45-10:15pm: Contested investigation scene on [issue B]10:30-10:45pm: Politics & scheming10:45-11:15pm: Player plot scene, relating to issues A, C and D (which the player's character is interested in)11:15-11:30pm: Politics & scheming11:30pm: End of official game time. This being an Elysium style game, time keeps going and players can keep scheming with each other, but the GM and game space are no longer available; and PvP conflict is relegated to between game activities, email schemes and discussion list arguments.
I like how you can expect a 7:30 arrival time if you say 7:00. I have no idea why punctuality is so poor for players...
I think for a one shot you don't divide by but by 5. 42 hours for a 7 hour game for 30 players seems closer to the mark. Campaign games have some of the basics done beforehand, anyhow.