Game Masters' Roundtable of Doom - The GM Intrusion

The Game Masters’ Roundtable of Doom is a meeting of the minds of tabletop RPG bloggers and GMs. Every GM has his or her favorite system, but in these articles we endeavor to transcend a particular system or game and discuss topics that are relevant to GMs and players of all roleplaying games.

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Here is this month’s topic:

What is a favorite mechanic or idea you've encountered in an RPG that you think would work well in other games? Please explain the mechanic/idea, tell us a bit about the game it comes from, and give some ideas of how it could be used in other games. You can discuss more than one mechanic or idea if you like.


My favorite mechanic that I like to consider applying to any RPG I run is a mechanic we’ve seen version of in a lot of games lately. My favorite iteration I’ve seen of this mechanic so far is in the Cypher System (e.g. Numenera), and in that system it’s called a GM Intrusion. FATE has something similar in the Compel, and the new Star Wars games (Edge of the Empire, Age of the Alliance, etc.) have the Destiny system.

Although we’re seeing this mechanic more and more (and as far as the examples I’ve listed, FATE thought of it first), I like the way it’s handled in the Cypher System the best. In this system experience is a currency that you can spend in play for benefits above and beyond leveling your character. One of the main ways you can spend xp during play is to reroll any die roll in the game.

An experience point is worth a lot more in a game like Numenera than it is in a game like D&D. It only takes 16 xp to gain a tier in Numenera, which is roughly equivalent to a level in D&D. I’m telling you this to give you a general idea of what 1 xp is worth.

When the GM wants to introduce a complication or twist into the story, he can use a GM Intrusion. The mechanics are simple. The GM tells a player that he wishes to introduce a GM Intrusion. The GM may or may not give the player some idea of what that Intrusion will entail, depending on the GM and the situation.

The player can then accept or reject the Intrusion. If the player accepts the Intrusion, the GM gives the player 2 xp. The player keeps 1 xp and gives the other xp to one of the other players. The player can award the xp for any reason, but she must state a reason (perhaps the other player did some good roleplaying, said something funny, or saved her character’s ass in the last encounter). The GM Intrusion then happens. If the player rejects the Intrusion, she pays the GM 1 xp, and the Intrusion doesn’t happen.

An Intrusion can be literally anything the GM wants, and he can do a GMI at any time. This is why I prefer it to the FATE Compel or Star Wars Destiny, which both have limitations on how, when, or how often they can be invoked. A GM Intrusion could be something as simple as dropping a weapon or accidently stepping on a pressure plate that sets off a trap. A GM Intrusion doesn’t necessarily have to be bad, although they often are, at least in the short term. The Intrusion should add something to the story, by making things more interesting, introducing a complication, raising the stakes, or even bringing some humor into the story.

The GM Intrusion is a beautiful mechanic for a lot of reasons. For one, it allows the GM to introduce an element to the story at the most dramatically appropriate moment, without having to rely on dice rolls (or fudging dice rolls) to make it happen. It allows the possibility of such classic story elements as the heroes getting captured. This is easy to do with a GM Intrusion (or a series of them), but can be exceedingly difficult to do in a system without this mechanic, mainly because the PCs are very capable and don’t want to get captured.

The best thing about this mechanic is it allows the GM to do all these things without having to butt heads with the players. Instead of having to cheat with the dice or remove player agency to get a story element in place, through the GM Intrusion the GM asks for the players’ permission and cooperation in introducing the element. This works especially well in the Cypher System specifically because the PCs get xp that they can then use for rerolls to mitigate some of the effects of the Intrusion.

I have been running Numenera for over a year with a variety of groups, and I’ve found that it’s surprisingly rare for players to reject my GM Intrusions. In fact, I can count the number of GMIs that have been rejected on one hand. This isn’t because my Intrusions are tame, in fact they’re often quite dangerous, but the players see the Intrusion as not only a way to earn xp, but also as a way to bring more fun in the game. I’ve found that the mechanic actually fosters trust and cooperation between the GM and players. So not only can the GM pull the tricks he wants to pull, but he can do it with the cooperation and blessing of the players.

GM Intrusions don’t always have to be bad. I had an instance in Numenera where I was facing a TPK (total party kill). It wasn’t because the PCs had done anything wrong, rather the published adventure I was running had included an encounter with a creature that was far beyond the means of the characters. I’m all for letting PCs suffer the consequences of their decisions (and hopefully learn from them), but I did not want a TPK due to a design flaw in the adventure I was running. If I’d been running another game, I might have had to “cheat” and fudge some rolls, but instead I used a series of GM Intrusions to remove the PCs from the sphere of influence of the creature. Now, it wasn’t a completely painless experience, but the GM Intrusions turned what would’ve been a TPK into a very close call that ended up with the PCs battered and scared shitless, but still very much alive.

The GM Intrusion gives the GM a lot of freedom to tell the story he wants to tell, and it builds a sense of teamwork around the table between the GM and the players. It helps convey that we’re all building the story together.

I’ve recently been running and playing the new edition of Dungeons & Dragons, and I’ve been considering how to use the GM Intrusion in that game (I suppose it would be a DM Intrusion). Since the GM Intrusion in Numenera effectively gives the PC 1/16th the amount of xp she needs to level, I first considered going that route with D&D. Unfortunately, this is a very inelegant solution. For one, the xp amounts you need to gain levels is not constant in D&D; the amount rewarded would have to be a function of a character’s level and would not be a constant like it is in Numenera. Also you end up with some very ugly numbers (not even whole numbers).

However, I think you can use the GM Intrusion by combining it with the Inspiration mechanic. Inspiration lets you make a roll with Advantage, which means you roll 2d20 and take the higher result, which is functionally the same as a reroll in Numenera (if you use the optional rule of letting the PC use her Inspiration after the die is rolled but before the result is announced). The only issue is that PCs are only allowed 1 Inspiration.

My proposal is to allow PCs to have more than 1 Inspiration. If a PC accepts a GM Intrusion, she gets 1 Inspiration to keep and 1 to give away (just as in the Cypher System). If she wants to refuse the Intrusion, she must pay the GM 1 Inspiration. I would also recommend allowing the PCs to use Inspiration multiple times on a particular roll, effectively getting a reroll each time they spend Inspiration. Inspiration can also be spent to give another PC Advantage (basically a reroll) on a roll, just as in the Cypher System.

I would recommend putting a cap on Inspiration. In the Cypher System, GMs are encouraged to make PCs spend xp if they ever accumulate more than 10, so I think 10 Inspiration is a good point to start with for a cap. You can try it out and adjust from there.

I think the GM Intrusion is a great mechanic to introduce into other games, and it’s usually not that hard to do so. I’m pretty happy with my idea for D&D, but I haven’t play-tested it yet.

Another possibility would be for the GM Intrusion award to be a die that a PC can add to a roll, just as the Bless spell and Bardic Inspiration work. This die could scale with character level, so a low level character would get a d4 to add to a roll, then at later levels the die could become a d6, d8, d10, d12 and eventually d20. However I think the Inspiration method is a more elegant solution, and it also more closely parallels the benefits that the system provides in the Cypher System.

We have to be careful when trying to apply mechanics from one game to another. We want to consider how the mechanic will fit in the overall system of each game and whether or not it’s a good fit in the new game. Another mechanic I like in the Cypher System is that the players make all the rolls, but this is a mechanic that just doesn’t work well in all systems.

The GM Intrusion is a good example of the type of mechanic you can translate to other systems fairly successfully. This is because the interaction of the mechanic with the overall system is relatively simple and doesn’t require a lot of changes (e.g. in comparison to having the players make all the rolls). The trick is to find the easiest way to introduce it, that will smallest number and degree of changes to either the mechanic itself or the system you’re incorporating it into. Finally, you want a solution that’s elegant and easy to understand and remember. That’s why I went with implementing the GM Intrusion mechanic into the Inspiration mechanic in D&D. Tying the GMI into the xp of the game would’ve been much more complicated, and anytime your solution has you grabbing for a calculator, you probably want to find a simpler solution.

Participating Blogs

Living for Crits by Jim Walls

Inspiration Strikes by Marc Plourde

Dread Unicorn Games by John Marvin

Files and Records by John Clayton

Strange Encounters by Scott Robinson