How to GM: Lessons Learned with the Best Campaign Ever

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I wrote before about my love for Masks of Nyarlathotep. I ran it 3 times. I wrote about my interpretation of its metaphysics. I wrote tips on how to run it. But I haven’t discussed how it changed my GMing style.

Running Masks of Nyarlathotep taught me that being a GM is not about controlling what happens.

Before, I ran improvised campaigns and valued player freedom, but I still had a tendency to fudge dice rolls from time to time, sometimes in favour of the players, sometimes against them, depending on what I felt would produce a more exciting outcome. Essentially, I felt responsible for what happened.

When I started running Masks of Nyarlathotep for the first time, and looking at its sandbox structure, I decided to make a clean break. Dice would only be rolled when the outcome genuinely mattered, and when they did, I would never fudge them again. To make that commitment irreversible, I started rolling all dice openly, in front of the players.

That decision changed things.

It helped me to stop trying to control outcomes. Instead, I focused on having my villains plan and execute their agendas using only the information they plausibly had, accepting uncertainty in exactly the same way the players did. Success and failure were no longer things I managed; they were things that happened. I have kept that “trust the system” attitude ever since.

It led to moments I would never have engineered. Major villains sometimes died before they could make their mark. Player characters were killed suddenly and brutally by what should have been minor threats. In one case, a character death caused real anger and a temporary rupture in the group. In another, a relatively weak monster rolled a critical success at the exact moment a player critically failed, resulting in a catastrophic and sudden death.

But there were also moments of earned heroism. Once, a player character chose to make a last stand against four cultists so that an NPC could escape. We were certain he would die. Instead, through a series of astonishing rolls, he killed all four: wounded, exhausted, but standing. That scene became mythic at the table precisely because it was not protected or arranged.

Another time, one character alone killed a Dark Young with an axe (if you don’t play Call of Cthulhu, a Dark Young is a monster tall as a tree, twice as large; it is horrifyingly deadly and has at times been responsible for TPKs).

Over time, the players start to appreciate something important: the dice are an equaliser. Just as a character could fall to bad luck, a powerful enemy could fall just as suddenly. That gave them hope. More importantly for me, it lifted a burden. I no longer felt compelled to justify bad outcomes or apologise for them. The mechanics separated me from responsibility for every life-or-death decision. That separation reduced stress enormously, and made the campaign feel fairer, harsher, more alive, and more exciting.

But surrendering control over individual outcomes creates another problem: over a long enough campaign, things will inevitably go badly wrong.

Running a campaign of this length also taught me that apparent “fail states” are inevitable. Over two years of play, there are many moments where it feels like the whole campaign has been compromised: too much went wrong, a key character died, a lead was missed, the situation spiralled out of control.

My response to those moments changed. Instead of trying to fix things immediately, I learned to keep a cool head and wait. Let things stabilise. Then ask a simple question: what is the next good dramatic question for the investigators to face? The important part is not the question itself, but whether it leads to productive situations, i.e. situations that demand decisions and action, rather than generating yet another dead end.

That shift, from fixing outcomes to creating productive situations, also changed the way I intervene during play.

I still hate void, and I know players often struggle to fully own the agency they are given. So I do intervene, but differently than before. I introduce what I think of as jolts of energy. These are not hints about what the players should do next, and not explanations from on high. They are events: danger, pressure, consequences, movement in the world.

A jolt has done its job when players stop talking about what they might do and start actually doing something. Explanations and clues must always be diegetic, which naturally limits how much information they can convey. I try to avoid both bad instincts: dumping too much information too soon, and hoarding secrets as if players were not allowed to obtain them. The goal is not to instruct, but to restore momentum without stealing agency.

And that means that letting go of control is very different from simply standing back.

Letting go of outcome control does not mean being passive.

On the contrary, running a campaign like Masks requires constant creation. Every meaningful action taken by the investigators generates consequences, and those consequences often demand new NPCs, new locations, and new encounters. A cult flees because the investigators burnt their sanctuary? They find a new place. A ritual is interrupted and the cult leader killed? A cult leader from another country comes to fond what happened. A lead is pursued in an unexpected direction? That direction needs substance, so it comes to existence on demand. 

The same applies to the antagonists. Villain agendas do not advance on their own. They must be serviced. This means regularly deciding what the cults do next, how they adapt, whom they recruit or sacrifice, where they hide, and what risks they take.

This is where the GM’s real discretion enters the game.

These decisions cannot be made on diegetic logic alone.

Plausibility is essential. I am strict about internal consistency, motivation, and causality. If the world stops making sense, immersion collapses. But plausibility is not the only criterion. When deciding how the world responds, I often ask myself two questions at once: What is most plausible, given what has already happened? And what is most exciting or dramatically productive right now? The art lies in finding answers that are plausible and true to the fictional world, but also exciting and dramatic.

Sometimes the most plausible option is dull. Sometimes the most exciting option strains credibility. 

Good GMing, for me, consists in finding the point where plausibility bends just enough to allow something charged, dangerous, or revealing to happen without snapping. 

This is also where restraint matters. Creation should serve momentum, not spectacle for its own sake. New elements should sharpen conflict, clarify stakes, or force decisions, not simply add noise.

Let us look at a small example. Imagine the investigators have just destroyed a cult lair and killed most of its members, but the leader escaped. The cult is badly damaged, the investigators have lost the trail, and the question is what happens next.

The most plausible option would be for the cult to halt its activities for some time. The investigators cannot track them. The game grinds to a halt.

A more exciting option would be for the leader of the cult, whose people have just been whacked, to attack the investigators alone. That would certainly be dramatic: he is powerful enough to take two investigators to the grave with him. But it makes little sense, because he would have to be suicidal.

So there is a third option. The head of the cult wants vengeance, but is not suicidal. He uses the resources he has left to bribe a couple of dirty cops, sets a trap, and ambushes the investigators with the cops and the remaining cultists.

The ambush must have a more than credible chance of defeating the investigators. They must have to do something out of the ordinary to survive it.

That is the sweet spot: an outcome that follows plausibly from what has happened, but still produces danger, pressure, and a situation demanding action.

Put together, these lessons have gradually changed how I understand the job itself.

After years and years of experience running games, I no longer see my role as that of a storyteller, a protector, or a referee. My primary job is to maintain momentum and emotional energy, while providing sensorial grounding. I try to put players in a state of mind conducive to action: by creating danger, by showing how evil the villains are, by showing what happens when they win, and by helping players believe that the information they need can be found.

I don’t choose outcomes. I don’t tell players what to do. I shape the conditions under which their choices matter.

That, more than anything else, is what Masks of Nyarlathotep taught me about being a GM.