This is part of a Gnome Stew double header. Click here to check out John’s article  for a look at collaborative GMing from a beginner’s perspective. It’s also a very belated response to AlasseMages’ suggestion in the pot.
Game Mastering can be a lot of fun, but it can also be a lot of work. Some of us simply don’t have the time or energy to devote to managing a campaign on our own. While the answer seems obvious (hand over the reins and become a player), things are not always clear-cut. Perhaps you are the only GM for the group and, without you the group dissolves. Maybe you’ve got a great idea for a new campaign that you want to see through, but your hectic schedule impedes your prep time. Maybe you want to see the current campaign continue but you need a break. Or, from John’s perspective as a player, you’re willing to step up to the GM’s chair as long as it’s a part-time position.
One issue with co-GMing is that it’s difficult to nail down a definition. “Collaborative” implies sharing, but some types of co-GMing require little in-session assistance between participants. In other cases, it’s absolutely critical for the co-GMs to work together during a session.
Another consideration is the reason why you feel that co-GMing is desirable. Certain types of co-GMing methods work better to solve certain issues than others.
Here are a few co-GMing methods that I’ve either employed or been a first-hand witness to, along with my reflections on each.
I’d venture to suspect that most of us have employed this method at least once, especially in modular class-and-level systems. Two or more GMs take turns running the group through adventures, usually changing hands at predetermined endpoints (e.g. “I’ll run the group through the Slaveport Trilogy; by then they’ll be fourth level and you can run the group through the Labyrinths of Law”).
A variant of the Tag-Team is the Side Trek, where another occasionally GM substitutes for the primary GM. These side adventures are usually self-contained.
I’ve never had a problem with tag-teaming, especially in D&D. One problem I did unfortunately sit through was a GM that didn’t take the tag-team opportunity and forced us to slog through low levels that he had no interest in running so that we could get to this awesome adventure he bought. Needless to say, we never played the adventure, since he bored us to tears long before then.
This is another old favorite of mine. Two or more GMs design and run a campaign world. Sometimes they operate in different locations (in a Superhero game, Lucy primarily runs games in Metro City, while Miranda runs her games in North Harbor), or perhaps one GM designs the world while the other GM creates adventures for it (the designer essentially becomes the “setting lawyer”).
In shared worlds, events from one GM’s adventures may get referenced or share NPCs with the other GM’s adventures.
Shared worlds are another very comfortable type of co-GMing for me. It’s the default assumption in modern games or games with an embedded setting (such as Star Wars or Babylon 5). I remember one Delta Green campaign where my co-GM took a favorite NPC of mine and roleplayed him completely differently. When I retook the chair, I played the NPC the old way. When one of my players commented on the changes, I just shrugged and said “the original actor was unavailable for those scenes, so we had to temporarily recast him.”
Believe it or not, rotating games is a form of co-GMing, and one that seems to be increasingly popular amongst my graying friends. Rather than collaborate on a single campaign, two or more GMs run separate campaigns on alternating sessions.
I’ve generally had good experiences with rotating campaigns. They’re helpful to players that can’t make a commitment to every session but can join one group full-time. They also allow GMs to control their campaigns while relieving them of the burden of a weekly grind. The only problem with rotating campaigns is that scheduling issues occasionally put long stretches of time between sessions (recently I joked to a player that our biweekly (fortnightly) sessions had become monthly sessions).
I first learned of this while reading GURPS (under the same title). The Adversary is a GM that plays the bad guys, usually in combat situations. Theoretically, the Adversary should have no knowledge of the PC’s abilities, although in practice this will only work for the first few encounters.
The World of Darkness LARP variant of this is the Narrator. While the Storyteller has the creative control, the Narrator is empowered to play certain NPCs and adjudicate challenges.
I’ve never had much experience with this beyond allowing a player whose PC died to play a villain throughout the combat (or her own charmed/hypnotized/zombified and now adversarial PC). I suspect that this works better in small doses unless the adversary GM is given some long-term goals.
The Covert GM
The covert GM is a co-GM that pretends to be a player while she is secretly working with the GM. Sometimes this collaboration is present at the outset; other times a player becomes a covert GM due to circumstances in play. Usually, the covert GM is ultimately at odds with the PCs and her revelation leads to a climactic fight.
An alternate is the Meta-PC (ooh, I created a new term!). The meta-PC is a PC run by a rotating GM. The other players realize that the PC has meta-knowledge of the campaign but trusts the non-running GM not to abuse the privilege.
This is one of my favorite tools as a GM. I’ve often used my “Body Snatchers” card to replace a PC with an evil counterpart and let my player in on the deception. Players are usually excited to play the role. I have, however, seen this played poorly, when a co-GM forgets what his evil powers are or tips his hand too early.
In large groups, especially LARPs or tournaments, the PCs may be divided into several groups, each with its own GM. The individual GMs may have an overall coordinator or they may gather together from time to time to keep each other appraised of what’s happening. Alternatively, again especially in LARPs, the PCs may interact with each other and grab whatever GM happens to be walking past when they need one.
I’ve seen this work very well at GenCon, and I’ve run a LARP. The only danger that I’ve encountered in tabletop is that one group may progress too fast, leading to downtime as they wait for the other groups to catch up. In LARPS, one GM may get the reputation of being “the final authority.” Once this happens, every player will line up to engage this one GM or attempt to get her to overrule another.
Back in the 1980s, I was part of a small group in a Marvel Superheroes campaign. Every player had a character (in some cases more than one) that was part of a superteam. On any given night, we’d roleplay the group hanging around the base and dealing with personal subplots (usually, one of the other players would GM a subplot for another player). Sometimes, one player would arrive with an idea for an actual adventure and assume the GM role for the duration. At other times, we’d commiserate over what we wanted to do and then one of us would get inspired to run it.
Sandbox co-GMing works surprisingly well in dramatic campaigns that are full of subplots, especially if the PCs have defined personalities and motivations. In spite of there being GMs, sandbox co-GMing is often the default assumption of a LARP (i.e. the players make their own stories).
Wrapping it Up
Those are my experiences with co-GMing of different stripes. As you can see, there are many ways of co-GMing, some obvious and some not-so-obvious. If you have any good or bad co-GMing experiences, please feel free to share them. I’m always looking for ways to lighten the load (as well as be aware of potential pitfalls)!