Welcome to the Megadungeon: Critical Path

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Welcome back to the Megadungeon!

It’s time to switch gears. Let’s get away from spreadsheets and XP and pacing concerns. It’s nice that we have an overall plan to guide us in building our maps and placing our encounters and s$&%, but we’ve been making a really big assumption. We’ve been assuming that we’re going to be able to keep the players on script for this whole giant dungeon.

When you get down to it, we’ve been building a sort of contradiction, haven’t it. After all, we’ve been talking about this big, wide open dungeon to explore, right? And the conceit of a good role-playing game is that the players have the freedom to choose their own path, right? And we’ve talked about how we’re going to let the players wander freely and explore, in fact, how that’s the point of the game, and how we’re going to reward it. At the same time, we’ve looked at the XP system and how adventuring days work and the pace of the game and we’ve come up with a pretty heavy-handed script for how the adventure will play out over 25 days of adventure. Can we have it both ways? And how can we have it both ways?

The answer is yes. Yes we can. But it requires us to utilize a couple of specific design tools. The first is called The Critical Path. And the second is called Gating. We’re going to focus on The Critical Path today. We’re not going to plan our critical path today, but we’re going to talk about it so that we CAN plan it. We’ve got to understand the idea before we can start mapping.

But before we do that?

F$&% Philosophy

As I’ve mentioned before, I’m not interested in debating design philosophy here in my Megadungeon. I have a specific vision, I’m working to bring that vision to light, and I’m not going to defend why that vision deserves to exist. That said, I do try to make it a point to acknowledge the potential arguments.

Critical paths and gates set of alarm bells in a lot of GMs’ minds. They smack of railroading. And railroading is something that we are traditionally encouraged to avoid. Mainly because of that whole “freedom” thing.

But when you actually sit down to plan or write an adventure, it’s impossible to offer total freedom. An adventure path that offers TOTAL FREEDOM is essentially a blank notebook and a pen. And no one will pay for that s$&%. Hell, no one who’s looking for a preplanned adventure WANTS a blank notebook. And even GMs who don’t run preplanned adventures usually have SOMETHING planned. It may just be a particular villain or a setting or a few encounters, whatever. But there’s something planned. Because it’s almost impossible to run a GOOD complex RPG adventure completely off the cuff.

GMing – and especially writing your own materials – is always, ALWAYS a matter of finding a balance between structure and freedom. And different GMs and different players enjoy different levels of balance. Moreover, no level of balance is inherently superior to any other. Idiots like to scream at each other about “sandbox games” vs. “railroad games.” Most of the people who use those terms are using them to establish a false dilemma AND a value judgement. That is to say that, inherent in that fight is the assumption that every GM must choose ONE or the OTHER and that there is a RIGHT choice and a WRONG choice. And that’s utter horses$&% and helps no one.

Sandbox and railroad are at opposite ends of a very, very broad spectrum of game structures. And every game lies somewhere in between. There are no pure railroads and there are no pure sandboxes. And if there were, they would be terrible games.

This is a published module. And it’s mainly about two things: explore this dungeon and discover the secret story and all the cool treasure AND are you a bad enough a$& to beat this dungeon? After all, it’s inspired by video games, so there’s a challenge element to it. And lots of players actually like that s$&%.

Now, telling a good story – even if it is just the story of a dungeon – is an inherently structured process. To be satisfying, stories really need to conform to our sense of story structure. Screenwriters know this and audiences respond en masse to it. There’s a structure to a good story, there’s a tempo, our brains are wired to want stories to fit a certain mold. If you don’t conform to it, lots of people (not everybody, but lots) dislike your story.

Delivering a good gameplay experience – one that is challenging but fair – is also an inherently structured process. There’s considerations like making sure the players have the opportunity to be ready for a particular challenge before they face it. If you suddenly blast the PCs with a deadly poison traps that kills half the party and they had no warning, that’s a screwjob, not a challenge. But if they had the opportunity to spend resources or take a risk to build up their poison resistance and if there were clues they needed it and they didn’t interpret those clues in time and gave up that opportunity, that’s fair. Because the players can look back at the situation and see what they could have done differently to create a better outcome.

At the same time, to tell a good interactive story, the game must change in response to the players’ choices. That’s what interactive means. And that’s inherently unstructured. You have no idea what choices the players will make until they make them. Moreover, in order for challenge to mean anything, the players have to have the opportunity to decide what challenges to engage and how to engage them. And their choices have to have consequences that make their lives easier or harder. And that, too, is inherently unstructured.

In the end, however, IN THIS PARTICULAR CASE, the unstructured elements are matters of pure perception. Look at the poison in the face gag. The fairness of that loss is entirely dependant on the players recognizing their mistakes. If they never see any other possibility, they won’t believe there were any. And thus, the situation becomes unfair.

So, the unstructured elements – freedom and fairness – rely on perception. The structured elements are solid, real things. That is, we have to present a megadungeon that appears to offer freedom, but is actually built on a solid structural foundation. We offer the players plenty of choices, but we also use a number of tools – incentives, soft nudges, and hard shoves – to keep the players from wandering too far from that structure.

And that’s the essence of what we’re doing. We’re building a dungeon that offers just enough freedom to allow the players to know they have choices while still keeping them from f$&%ing up too much of the structure.

The Critical Path

So what is “the critical path?” Well, critical path is a project management term, but that meaning doesn’t help us here. We’re going with the video game definition. In a videogame, the critical path is the shortest, most direct route from the beginning to the end. You might think of it as the shortest path through a maze. But there’s more to it than that.

Imagine there’s the Hexahedrous the Euclidean has constructed a dungeon of exactly 16 rooms with only one entrance from the outside world. And imagine that he has hidden the Hexagonal Ruby of Orthagonalian somewhere in the dungeon. The heroes have to go in and find it. Now, first examine this layout.

Grid 1

Note that every room is connected to every adjacent room. Now, imagine a group of heroes enters the dungeon looking for the ruby. And imagine, after they clear each room’s challenge, they choose an exit at random. At minimum, the party must clear three rooms before they enter the room with the ruby. At maximum, the party can clear up to fifteen rooms before they enter the room with the ruby.

Put that in a D&D context. Remember that, in D&D, players will face four to six encounters in a day because of the mechanics of attrition and challenge. And those encounters should definitely reach a climax right before the day ends because of the needs of story structure.

We have no idea what path the PCs will take during the day. We can’t plan our encounters or our climaxes. If they randomly end up exploring all fifteen rooms, it’ll take them three to four days of adventure to clear the dungeon. If they end up exploring only three, they are done after half a day.

As a GM, I don’t want that level of uncertainty. It prevents me from building a good adventure from a gameplay or story perspective. So, imagine I use this layout.

Grid 2

Note that every room has exactly one exit. What that means is that I know the exact path any group of adventurers will have to take through the Euclidean Fortress to recover the ruby. And I can plan my challenge curve and my climaxes accordingly.

But notice that, in doing so, I’ve taken any exploration element whatsoever. There’s no freedom. The players simply follow the path I’ve laid out for them, dealing with one obstacle after another. That structure is boring. It isn’t fun. THAT is a railroad.

Let’s look at the third option.

Grid 3

It might look like I just connected the rooms at random, though if you’re clever, you may already have spotted the method to my madness. Take a careful look at that map and see if you notice something. Maybe this will make it easier.

Grid 4

What’s special about this design is that this design has a critical path. Actually, it has two paths, but both of them are the same length. In order to get to the ruby, the party MUST traverse seven rooms. Seven SPECIFIC rooms, though, including the branch, there’s a total of nine rooms they COULD go through.

That knowledge, the knowledge that, no matter what else the party does, they must traverse a specific series of rooms before they can have their goal, that knowledge is extremely valuable. Because I can build an adventure structure along that path. At the same time, I allow the party to deviate from that path by adding side passages. Heck, I even have one branch where the party can choose between two different paths to their goal.

At the same time, there’s all these little side treks the party could take. If they explore at random, they actually COULD still cover fifteen rooms before they find the ruby. And that means they will have to retreat and rest and return a few times. No big deal. But I can still build around a good structure.

For example, room 11 and room 16 are optional encounters. Imagine I put a lava trap in room 11 that, if the party sets it off, reduces the whole room to impassable lava. Well, now I know they can still find their goal. Whereas if they render rooms 3, 4, or 8 impassable, they’ve lost the adventure, right? So I’d better have a plan for how to tell them they lost.

Or, alternatively, I can place a tough fight encounter in room 11 and a tough riddle encounter in room 16, so the party can choose muscles or wits. And because I know the party has to go through room 14 before they see either of those rooms, I can build a clue in there that says “wizards should not tread north and warriors should not tread east” or some bulls$&%.

Also, if I have a boss monster and a sub boss monster and a tribe of henchmen, I can put the henchmen in room 14, the sub-boss in room 12, and the boss in room 3. That way, I know the party won’t encounter the hobgoblin leader before the goblin priest and I know they won’t encounter either until they encounter at least one pack of goblins.

But there’s even more I can do with a critical path. For example, if I want to encourage exploration and reward the players for it? I can stash an icon in room 6 that diminishes some of the goblin priest’s powers. And I can hide a letter in room 13 that explains that a hobgoblin was dispatched the lead the goblins. And in room 1, I can have an optional encounter that has some pretty cool, useful treasure for the next adventure. But I’d better not make that encounter TOO hard because the PCs will have just finished off the dungeon boss.

And if I want to discourage exploration? Well, I can lay a trail that shows the PCs the critical path. Maybe they can track the wizard somehow. Or those passages have been used frequently while the other ones are dark and dusty and misused. And further, the side passages are filled with vermin and don’t have any treasure to discover. After the party hits the dead end at room 13, after fighting giant rats and spiders and discovers nothing but a looted storeroom filled with debris and junk, they probably head back to the path and get the message. And if they don’t, they keep wasting resources until they figure it out. But that’s their fault.

So, the critical path is a pacing and planning tool. It allows us to know where the party has to go, to plan the pace of adventure along that path, and to drive adventure along that path if we want to or else to reward wandering from that path.

But how do you recognize the critical path in your dungeon and plan accordingly?

You don’t, f$&%wit.

How Critical Paths Happen

Critical paths don’t just happen. They aren’t an accident of dungeon design (or any game design). You design the critical path and then you design the rest of the dungeon around them. You probably figured I was going to say that.

And frankly, designing a critical path is easy. It’s just a matter of drawing a windy line and adding the right number of encounters off of it. Seriously. I s$&% you not. There’s no great magic to the critical path. Granted, turning the thing into a dungeon is a different matter entirely. But we’ll get there. One step at a time.

After you lay down your critical path, you can add branches or bypasses. Forks. It’s easiest if the forks all have the same numbers of encounters and obstacles, but they don’t have to. You can make an easier path and a harder path and you can give clues so that players can figure out which is which. Or not. You can just leave it up to luck.

After you lay down the branches, you can add side paths – the optional areas. The more you add, the more difficult it will be for the players to follow the critical path without a lot of extraneous action. But the more side paths you add, the more room you have to add optional content like treasures and hidden rooms and clues to puzzles along the critical path. Whatever.

Critical Paths

And honestly, that’s it. I mean, I’m sure you expected something more complicated with more spreadsheets. But some of this stuff is actually kind of simple once you understand the utility. The thing is, though, that the critical path is probably the most important planning tool we’re going to use alongside our big ole spreadsheet of what happens every day.

And don’t worry, next week,. we’re going to complicate things by talking about gating.

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18 thoughts on “Welcome to the Megadungeon: Critical Path

  1. This article, especially in juxtaposition with “every adventure is a dungeon”, was particularly helpful. Thanks!

    • One concept at a time, I think.

      I note that any jaquaying that occurs will have to be either in the form of “branches”, which he has already discussed, or “side paths”, and that any jaquaying involving “side paths” must to so in a way that does not negate the critical path.

      I believe we will see some jaquaying with the shortcuts he has referred to. However, I expect it will also be important that the dungeon not be jaquayed in a fashion to negate the gates he will be putting in.

      Because there are so few encounters per level of advancement, there may not be a lot of room for jaquaying if the dungeon segment is only intended to cover a single level. There would be more if it covered, say, three levels. I am curious to see what he does with this; is he going to put gates after every level in order to organize the dungeon in smaller chunks, or have it span more levels to allow more freedom of choice?

      I note that the latter also plays into the “ratcheting” concept he discussed in an earlier article: if the party starts the dungeon segment at level n, and is expected to leave it a level n+2, and the all of the encounters are on average level n+1, then it will start out hard and get easier as you go along. On the other hand, if the dungeon segment is large, it makes it harder to control what level the party is at particular areas in it. So I am curious to see how many critical encounters he places between gates.

      • Jaquaying is different since one of the assumptions of the Critical Path is that there is only one entrance. The Critical Path breaks down when you add in that element.

        • Yes, the jaquaying would have to happen within the dungeon segments i.e. between gates. Each area between gates is essentially its own adventure.

          Note that if there are three levels of play between gates, that is essentially the same size as the dungeon portion of Keep on the Shadowfell, which was jaquayed as an example at The Alexandrian.

          Also note that you could still, effectively, have multiple entrances if you had branches occurring immediately after the gate. Or if the gate was actually three gates (which amounts to the same thing). Like, say, the gate included a room that had a main exit, a sinkhole, and a secret door.

        • And to quote part 3 of the essay from The Aelxandiran, “None of this, however, is to say that you should never use branching paths or create chokepoints for accessing the lower levels of the dungeon. (Any more than it is to say that every single means of egress should be secret or unusual.) It is merely to say that such features should be used to effect and not simply by default.”

        • Yes, agreed.
          IMO Jaquaying is generally superior to Critical Path for megadungeon play; it creates a far superior exploratory element – and exploration is supposed to be one of the Three Pillars of 5e D&D. Most WoTC dungeons use Path design, and it certainly has its place, eg in creating a climactic series of encounters. But I don’t think the entire dungeon should be Pathed, that is a huge waste of potential. Much better to have the bulk of it Jaquayed, open to exploration via all sorts of routes, and then have Pathed mini-dungeons within it.

          After 3rd level XP & rapid progression is much less of a problem than is being assumed here. Use groups of lower-CR foes and the PCs can be challenged perfectly well while advancing no faster than in older editions.

          • One feature of traditional Megadungeon play is that PCs often have the opportunity to set their own risk/reward level by deciding how deep to go. Gates seem designed to stop that sort of decision making and ensure everything encountered is beatable.

          • I believe gates are designed to ensure that at least enough exploration takes place to gather the elements necessary to open the gate. Whether this discourages exploration depends on the group involved. I don’t think I have run or played in a megadungeon since the 80s, but IIRC stairs going down were as good as a gate, since they were effectively a sign saying “tougher monsters this way”.

            I also recall that the power curve was pretty flat, and that the expectation was that parties would be pretty large (Dark Tower was 6-10 characters of levels 7-11), so in general there was rarely anything a party could encounter while fresh that it could not, in theory, handle. And none of those old dungeons spanned 10 levels – unless you count things like the GDQ series, which had all sorts of gates between modules. The Dark Tower itself was only levels 7-11. Temple of Elemental Evil was only levels 1-8, and there were effective gates everywhere: Hommlet to Moathouse to Nulb to Temple; not to mention the role that ACTUAL GATES play within the Temple.

            In short, you don’t actually know if the problem you are complaining of is going to exist. .

      • Right, Angry obviously has a system he’s trying to teach us. It seems premature to suggest that Angry should go to school. Let us see the system and offer critiques or kudos once the dungeon is built. He has particular objectives in mind (ratcheting, gating, etc). Let us see how well those objectives are met.

        • Hey, thanks for that. But I’m used to people telling me “well, you should handle this better” before I actually finish the f$&%ing product.

          I will say that Jaquaying is misguided in a project like this. There’s a lot of good reasons NOT to do this. And most of the benefits of Jaquaying are only visible when the same group plays the dungeon multiple times to completion. Which is an old-school practice that really isn’t done nowadays. There’s no real need to add “replay” value.

          • Hey, interesting articles. Some good insights here.

            If it were me, I would be a little more loose with stuff, but I can see the advantage of your approach and I’m sure down the line you’ll be able to give some pretty good demonstrations of the advantages of your sort of “planned freedom” approach.

            I hadn’t come across the idea of Critical Path in dungeon design before, and I like it quite a bit especially as a starting point. It allows the skeleton of the map to be designed quickly and simply, which I like.

            I still think a mix of Jaquaying and Critical Path is best though – Jaquaying for the entire dungeon “superstructure” and Critical Path for the “mini-dungeons” inside. Because as you say, and I agree, Jaquaying is mostly relevant for repeat visits, and the adventurers will visit the superstructure over and over and over again perhaps from different angles, but once they are “done” with a complex, they will probably not reivsit it. I like to think of it in terms of “thoroughfares”, “complexes” and “hubs”. Thoroughfares are the main travelways in a dungeon – long passages, underground rivers, mine cart tracks. Hubs are where multiple Thoroughfares meet. And a complex is any area with a unifying theme or faction. Thoroughfares and Hubs should be Jaquayed, but without really knowing what it was, I think Complexes should use critical path.

            Thanks again, looking forward to more.

    • That excellent essay series is about map building. I don’t think Angry has led us into that territory quite yet. We’re still looking at things from a more big-picture design perspective of how encounters link together. Yes, the map does inform and is informed by the encounters, but jaquaying is more appropriate later in the process.

  2. Well, this is not strictly connected to the idea of the critical path, or even to the megadungeon, but I would like to show you the ‘paths’ of one of the first single-session adventures I made for my group, quite some time ago. It’s an example of how to use the scene structure when planning an adventure. It does have plenty of flaws, which I believe is because it was one of the first adventures I made, but it still has its merits, I believe.


    (text intentionally illegible because I don’t like the specifics of my adventures being known outside my group)

  3. You said, “At the same time, to tell a good interactive story, the game must change in response to the players’ choices. That’s what interactive means. And that’s inherently unstructured. You have no idea what choices the players will make until they make them. Moreover, in order for challenge to mean anything, the players have to have the opportunity to decide what challenges to engage and how to engage them. And their choices have to have consequences that make their lives easier or harder. And that, too, is inherently unstructured.”

    When I was gaming more regularly, a number of my players become DMs over the course of several years. This was exciting to see, and I played in their games to support them. Almost all of them tried to tell a story they had imagined in advance. A story they had spent a lot of time working on. A story that they were too scared or unwilling to diverge from at the table. I’ve seen people run published adventures in the same way.

    It wasn’t much fun to play in those campaigns. This was before popular internet communities and your blog, but from what I read online, this is not an uncommon experience.

    I know you don’t like to get into debates about railroads and sandboxes, but it’s not really that. If you’re writing for new DMs then I think it’s is an important topic to cover. In my limited experience it seems like the pre-determined story is a common new DM problem, and even for experienced DMs its all too easy to get overly attached to things that get destroyed or never seen by the players.

    You’ve mentioned bits of this in various places and there’s other advice out there, but I’d really appreciate an in-depth article with your advice on preparation techniques to allow for player decisions, letting go of preparation that doesn’t get used, and how to demonstrate consequences of player actions over time.

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