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Grand Experiments: West Marches

West Marches was a game I ran for a little over two years. It was designed to be pretty much the diametric opposite of the normal weekly game:
1) There was no regular time: every session was scheduled by the players on the fly.
2) There was no regular party: each game had different players drawn from a pool of around 10-14 people.
3) There was no regular plot: The players decided where to go and what to do. It was a sandbox game in the sense that’s now used to describe video games like Grand Theft Auto, minus the missions. There was no mysterious old man sending them on quests. No overarching plot, just an overarching environment.

Start A Campaign – Part 4: How to prepare a great game in less than 30 minutes

Generate or use a pre-made map. Gryphon from community3e.com suggested an old Ravenloft map or real castle maps in this article on DM tools. (5 minutes)
Don’t bother with planning the descriptions too much but focus on one element to set a mood. Constant rain. Darkness. A smell. Anything that you usually don’t do. Stick with it and your players will feel the tension from the outside element that’s gnawing at them. (2 minutes)
Generic monsters. No time to mess with the latest weirdo from Monster Manual 7: Underwater invertebrate beasts. Go for a goblin, a giant, a wild animal. Just bookmark a book or scribble the stats down. (3 minutes per encounter)
Spice up each encounter with something special. Make it very obvious that there is something different about an encounter. For example, the characters meet a lone gnoll with a shiny silver 2-handed sword. That’s unusual. It will keep them on their toes and it’s not much work to think of a single weird fact about each encounter. (2 minutes per encounter)
Add a situation that involves a riddle to the game. Just google riddles. There are hundreds of websites on riddles – all ugly as hell apparently, so I don’t want to link to them. (5 minutes)
Reuse old material. I always prepare scenes that I end up not using because my PCs have a knack for the unpredictable. I also reuse maps of places they have already been to and they never notice. (5 minutes to dig up the old stuff)
Bring back an old problem or villain. You can worry about explaining the return to life of a fallen enemy later. Just bring back the villain (3 minutes)
Polish the most lacking aspect of the game you just planned. (5 minutes)

What to do in-game to make sure you don’t run out of material
Let the players role-play.
Encourage role-play by being lively when impersonating NPCs.
Fudge the monsters’ HP if a fight isn’t long enough or hard enough. N.B.: If you are a player, know that your DM will never do that. That was a joke. EDIT: I wrote more on this topic: 18 ways to increase combat duration.
Give the PCs a mysterious magic item. It is mysterious because even the DM has no clue what it does. The players coud spend hours toying with it trying to figure it out. Eventually they’ll come up with a guess about what the item is for and you can just go with the flow and confirm the players’ guess.
Award enough XPs for the characters to level up. That’ll eat up 30 minutes or an hour.

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