Is Running Two Game Masters a Disaster?

Roleplaying Tips Newsletter #1031

RPT Patron Morgan Joeck asks about having one campaign with two game masters:

A friend wants to run a dungeon crawl, and I like the concepts behind Demonplague.

I was wondering how you would suggest co-DMing the campaign.

How much of the through line is there between the four modules?

Would GMing the first one or two “spoil” the others?

What sort of continuity in planning needs to happen between them?

Thanks for the great tips all of these years ?

First let’s talk a bit about co-GMing. Then I’ll cover your Demonplague questions, Morgan.

Shared GMing seems like a great idea.

Each GM can help with prep.

Players can play more often (two GMs = better scheduling if it requires only one for a session.)

Or GMs get more rest or planning time between sessions (GMs alternate).

If both GMs are present, players get more spotlight time.

And two GMs means more ideas, better ideas, deeper planning, and other benefits coming from two brains pitching in instead of one.

Danger, Danger

I’ve had mixed success with co-GMing. First, let’s talk perils.

It’s a marriage. So pick your partner with care.

It’s a dance. So pick your partner with care.

It’s a partnership, so mind your game with care.

In one instance, I saw both game masters compete for their ideas. The players were audience and victims of this conflict. Not good.

Another time, both game masters were playing a game between themselves. They enjoyed this to the group’s detriment. Players were mere pawns in their manipulations.

In an another game, I saw communication break often. Neither GM filled the other in on what was happening. So, the game devolved into confusion, chaos, and lots of ret cons.

Before committing long term to a co-GM campaign, try a one-shot. Get group feedback afterwards.

Ensure GMs communicate well. Set up ways for GMs to check-in or chat without interrupting gameplay too much.

Most important, make sure game masters are compatible and can keep the gaming experience good and consistent.


In the co-GM campaign, I ran, we had an amazing time.

We leveraged Fog of War. With two GMs, we split the party or single out PCs often.

We had two rooms. When characters split off, a GM took them into the second room.

We agreed to check-in when timelines advanced more than a few minutes. We also agreed to check-in when actions in one room could impact the other.

Check-ins were brief meetings in the hallway. We planned before sessions, so we just needed to update each other on logistics: who, what, where, when, how.

As part of our Fog of War Strategy, we leveraged foes with magical darkness and shapechange powers.

This worked awesome. With players separated, we ran perception checks and shared information with no chance of meta gaming.

The peak moment came during a fight in the villain’s lair where the party had split in half. Each group thought the other was the enemy and attacked.

When the players realized they were attacking each other, they learned one or more of them were doppelgangers.

This resulted in fantastic roleplaying and tense moments as PCs tried to use logic, interrogation, and tricks to figure out which PC was an imposter.

In another co-GM game, we worked great as a team on prep and ideas. One GM took the lead during games and the other ran NPCs and foes in combats.

The format can work. And work well.

For advice on how to run two-GM campaigns, I recommend checking out these tips:

Running The Demonplague with Two GMs

I think the way James and I wrote the campaign sets it up well for co-GMs.

Campaign structure is a classic storyline embedded within sandbox embedded within a hexcrawl.

We give clear boundaries so you don’t get hit with the classic sandbox pitfall of an infinite world to prepare. The entire premise of the story takes place within the Luna Valley.

So you can let the players wander — even encourage them to do so — without fear of having to do much back-end work and co-GM coordination to account for player choice.

A series of preset encounters covers you for any player choice or direction. Those encounters have built-in plot hooks and story development.

This means either GM can grab an encounter “out of the box” whenever they want without fear of messing up the story. This is ideal for co-GMing, though we did not write with two GMs in mind.

Last, the hex generation system we present lets characters explore any unmapped parts of Luna Valley with instant area stocking and encounter ideas. An ideal setup for two GMs who might want to add in their own spice and have room to do so. Plus, it helps either GM account for players wanting to discover new and exciting things during the campaign.

So the structure works well for co-GMs, perhaps even better than traditionally written adventures.

NPC Bonanza

As you know, I love my NPCs. They are game changers, both in the literal and the bad pun sense.

The Demonplague has dozens of NPCs. Each carefully illustrated full-body to show you what they look like and their demeanour.

We created a bonus PDF that has every NPC laid out, one per page, with description and plot hooks, along with space for notes.

Print this out or mark them in the PDF to assign one GM per NPC to manage, plot, and roleplay.

That would be pretty freaking fantastic. Two brains giving those awesome NPCs time and attention.

And those NPCs cause fantastic game conflicts, roleplay situations, and encounter hooks. One is a serial killer. Another is a corrupt council member. Two are having an affair. Several have secret pasts they want kept that way.

And each wants something in this new, post-apocalyptic world.

Yes, co-GMs would work well here, either through divide and conquer or assigning one GM to manage the NPCs while the other works on different aspects of the campaign.

It’s A Dangerous World Out There

The campaign is robust.

A glacier that once covered the Luna Valley disappeared. Characters can now discover ancient secrets. If players want to explore the valley for exciting encounters and discoveries, no problem.

If they want to stick around town and delve into its intrigues, that ‘s great.

The story has hooks for you and progresses in either case. We offer a villain actions list and timeline. You can run villains in the spotlight or as drivers of background events to make the milieu deep and dangerous.

The adventure supports combat-heavy style, roleplay-heavy style, and points in-between.

So, The Demonplague can accommodate different GM tastes.

How much of the through line is there between the four modules?

There is a strong through line throughout the entire adventure.

And for the reasons described above, it serves co-GMing well because you can both agree on how much spotlight to give the story.

Even better, James and I designed the adventure to survive first contact with the players.

Whether the players spread the plague or stop it early on, the plot continues.

If your PCs kill the first villain by a fluke in the first encounter, or if the necromancer escapes and harasses the PCs the whole campaign, it’s no problem.

And if the PCs ignore the town and head straight for the wilderness and dungeons, or if they stick around town and ignore the wilderness and dungeons, the storyline remains relevant, urgent, and intriguing.

It’s also cool to see via the Demonplague Facebook Group how GMs are adapting the campaign and the story to their worlds and players. It’s really a toolbox designed to drop in anywhere and give characters a run from their lives.

Would GMing the first one or two “spoil” the others?

Do you mean plot twists and secrets will get spoiled if one GM wanted to become a player?

If so, yes, there would be spoilers.

We give each NPC hooks and secrets.

And we sprinkle NPCs throughout the whole campaign (communities, wilderness, dungeons).

There’s always someone new to meet, a new villain to introduce, and a new side plot to engage with.

You could keep the locations of key areas undecided until game time to prevent GM-turned-player meta gaming or having to hold back a secret.

Likewise, you could change features and leave it to GM fiat to prevent spoilers. Change who is the serial killer, who is running from the Safeharbour mafia, and what kind of foe a villain is.

We lay the overall plot arc out in part one. But even knowing the ultimate campaign premise and aim, it’s minor compared to how the players interact with the adventure each session.

By that I mean we coded in multiple endings. And the journey is fraught with unknowns and key player choices. So knowing the plot arc still leaves a ton of room for surprises.

What sort of continuity in planning needs to happen between them?

The core plot involves stopping a great evil from returning. It involves several villains and adventure sites. And you can run several side plots, such as stopping a slavery ring, preventing or mitigating a communicable plague, stopping allies of the main villain, ensuring a fair election, and more.

First decide how you will structure the co-GMing. Read the 5 Tips on Co-GM Campaigns article for specific examples and categories of planning.

Once you have figured out how you want to GM, and what you each want to GM, then assign The Demonplague parts to each GM.

For example, if you’ve shared story development and make one GM the combat GM and the other the NPC GM, then you must run post-session planning meetings on the storyline to account for session developments and player choices.

If you’re going to both share everything and handle the campaign more in a Fog of War or split party fashion as my friend and I did, then you’d want to flesh out the map with encounter locations, decide how you want to handle hexcrawling (e.g., roll in-game or create several hexes ahead of time to drop-in), and figure out how you want to coordinate in-game.

You’ll want to coordinate on player preferences and character integration.

Plus, agree on where the Luna Valley exists in your setting.

Figure out world conversions for gods listed in the sidebar at the front of the book, currency, cultures and races, and big picture events that could affect campaign play, such as a war you’ve got brewing nearby.

Read over the new monsters we designed and agree on their inclusion.

You might want to mesh Luna Valley’s backstory, and major NPC back stories, with your setting’s history.

James and I made the whole campaign “drag and drop.” You can run the campaign with minimal prep and no pre-established world.

Finally, talk about campaign vision, session operations, and who’s supposed to do what.

I hope this answers your questions, Morgan. If not, shoot me another email.