Today’s guest article comes from reader BryanB, who tackles one approach to running non-linear adventures in a comprehensive, usability-focused way. Thanks, Bryan!

I used to use a fairly linear approach to adventure design, much like the writers of a typical module utilize. I’d often do a painstaking amount of detailed game prep. As many of my players tended to go off path during an adventure, I grew tired of seeing more than half of my preparation effort never see any use at the table.

A GM can plan six different outcomes for a plot arc and the players will usually find number seven — the one that the GM didn’t think about. Around fifteen years ago, I was completely burned out and tired of the linear approach. It just wasn’t working for me any longer. So I came up with a new way to approach my adventures. I didn’t know that I was stepping into a “sandbox” when I did this, but in retrospect that is pretty much what I did.

This method is something I refer to as the “Matrix Method.” Using this approach has saved me a lot of time when planning an adventure series or campaign. It has worked for Star Wars, D&D, Top Secret S.I., and just about anything else I have ever run.

We’ve had a lot of good articles here on the stew about the sandbox form of adventure design: Nonlinear (Sandbox) Games, Dynamic Sandboxes, Connect the Dots and Get to Work, You Can Use Your Sandbox Too, In Defense of Railroading, and Nice Myth, Ugly Truth: Sandbox Games are Better. This article comes at running a sandbox game from a different perspective.

I have tried to break it down as simply as I can. The level of detail you might use may be different than the level of detail that I or others may use. Detail is often a matter of personal taste. Many of my past players have asked me how I get my games to contain so many “wheels within wheels” subplots, deep conspiracy elements, and webs of political intrigue without having copious amounts of detailed notes or fully fleshed out plot trees. This is how I do it.

The Matrix Method

While each genre has individual characteristics to consider, the basic planning of an adventure can follow a similar approach. Obviously these methods work best for a series of linked adventures, since a one-shot or convention event game is constrained by being a single game session with no long-term story development over time. The Matrix Method might help a GM sort out his thoughts for a one shot game, but the time limits involved must be taken into consideration.

To me, the interaction of PCs and NPCs is the fuel that drives the roleplaying engine. The key component of that interaction is motivation. Great players need great adversaries. Nothing captures the excitement of the roleplaying medium better than an epic villain and his minions being challenged by a band of heroes. Like the best movies, the players must have an antagonist or two or three or however many make the game most enjoyable. The PCs also need an ally or two to offer guidance or direct assistance. To use the Matrix Method, we need to know who is going to interact with the player characters.

When I sit down to work on a campaign, the first thing that I think about after genre and premise has been chosen is something similar to what detectives do when they work a crime scene. The basic thought process follows this pattern: Who? What? When? Where? Why? And How?


Thus the key first step in the process is called the “Who” step. You have decided the genre and setting that you want for your campaign. You have decided on a basic premise (mercenary band, outlaws, knights, spies, etc.) for the overall adventure series. But you need the movers and shakers for your adventure path. I make a list of all the major NPCs that spring to my mind as potential allies or enemies at the start of the series. This list does not have to be overly detailed. You can fill in the details as needed.

Let us keep it simple and say that you have listed ten major NPCs for the series. Now, you have a list of ten NPCs. You have a name, perhaps a profession, a title, their gender, their race, and perhaps a snippet of information on their appearance. It is important to make a note if any one of them knows one or more of the others. You now have the major players for the area, town, city, or a galactic star system. These are the important NPC cast members for your series. Each of them probably has numerous flunkies, agents, guards, thugs, or whatever you want to classify them as.

Alright. You’ve got some great NPCs created. This really isn’t that uncommon a planning step right? What makes this any different from a linear approach?


The next step in the Matrix Method process is the “What” step. What is each of these NPCs currently doing at the start of the campaign? What have they done recently? What are their short term goals? What are their long term goals? What is their current agenda? Having already listed the major NPCs for the series, you simply give each NPC their own notes covering what they are doing.


“When” is the next step in the planning process. This is an important step. This is where you create a timeline of pre-planned events. “When” relies on what and who to create the campaign’s projected timeline. You know who is doing things and you know what they are planning to do. When do they plan on doing these things?

When will each step fall into place? This timeline is flexible. The character’s actions could totally alter this timeline of events. If the player characters choose not to act, an NPC’s actions could continue towards completion! If two NPCs are in league with each other, what will happen to their plans when a part of their plan has to be altered?


The next step in the process is “Where.” Where are these events taking place? Obviously, this is dependent on what is planned and who is planning it. These notes are placed alongside the “When” notes. You now know who is involved, what they are doing, when they are doing it, and where they are going to be when it is done.

How are they going to do it? This is our next step. “How” is tied to the “What” more than anything else. You know what the NPC and his associates are going to do. You already know when these events are projected to occur. How will they carry these events out? How do they accomplish each step in their plan? How do they deal with the PCs aiding or hindering their plans? How will their resources be distributed?

And Why?

“Why” is the final part of the Matrix Method planning process. Why is the NPC doing these things? “Why” is where we note the NPCs motivation. Why are two NPCs allied? Why are two NPCs blood enemies? Why does that NPC want to plot his what, when, where, and how? You can get a lot of mileage out of this step for if you know why someone is doing something, you can easily determine their reaction to being interfered with or perhaps aided.

An NPC example:

  • Who: Baron Manfred Von Richthofen AKA: The Red Baron
  • What: Become the greatest ace in the world by shooting down all enemy pilots he faces.
  • When: Each time he takes his plane into the air, at least once every other day.
  • Where: In the skies over the European Theatre (WW I).
  • How: By flying with squadron mates or by personally challenging Allied pilots to a duel.
  • Why: Before the war, he had been a national champion horseman, and had grown fond of trophies and ribbons. As a child the walls of his home were heavily adorned with trophies of the hunt. It is then not surprising that during the war, he awarded himself with an engraved silver cup for each Allied plane that he downed.

After creating this information for each major NPC in a series, I will have a plethora of ideas for how the series or campaign can flow. Thus a “matrix” or web of campaign events is set in motion. If needed, I can make adjustments on the fly simply by checking an NPC’s motivations (Why). All I need to do to get the characters involved is to set the table with an opening adventure hook. The conflict or cohesion of NPC motivations and player motives/actions will take care of most of the rest of my session planning.

It is the players that will have the greatest impact on the story arc, since it is the players that decide their course of action or choice of inaction. This is a very flexible planning method but it requires at least some of the group members to have a pro-active play style to achieve the best results.

I hope this gives you help in your planning of a sandbox type of campaign or at least gives you a few ideas that will spark your own methods or approach.

Author’s note: I once posted much of this information on the gaming forum RPGnet under a thread that I started using the user name PaladinCA.