RPG Evolution: Eat or Be Eaten

Megadungeons, long a staple of D&D, can be just as complex as any other ecosystem in your campaign.

1200px-TrophicWeb.jpg

Picture by Thompsma - Own work, CC BY 3.0, File:TrophicWeb.jpg - Wikimedia Commons

The concept of megadungeons conjures images of sprawling underground complexes filled with untold riches and deadly monsters. But beyond the treasure and encounters lies a deeper level of worldbuilding: its ecology. Considering the intricate web of life can transform a static dungeon crawl into a living campaign. But to make that ecosystem matter to the PCs requires some planning that can make simply killing a monster change the course of the game.

Dungeon Ecology Basics​

For a dungeon ecology to truly resonate with PCs, certain elements need to be in place (see Lew's article on the same subject). Firstly, the dungeon needs to be large enough and have multiple levels to support a diverse ecosystem (Megan Wiseman calls this "Gygaxian Naturalism" after co-creator of Dungeons & Dragons, Gary Gyax). Different levels with varying resources and environments can host distinct food chains and monster populations. A small, linear dungeon simply won't have the space for a complex web of life.

Secondly, repeated visits to the dungeon are key. If the PCs are delving into the same complex over multiple sessions, they're more likely to observe patterns, note changes, and perhaps even develop a sense of how the dungeon "works." Why bother learning what eats what if you're only planning a one-time raid?

Finally, the possibility of PC impact on the ecosystem should be apparent. If the adventurers' actions – whether through hunting, introducing new creatures, or altering the environment – have noticeable consequences, they will be more invested in understanding and perhaps even manipulating the dungeon's natural order.

The basics of ecology involve trophic levels, each with its own level in a food web:
  • Level 0 (Decomposers): Often left off food webs, these involve creatures responsible for breaking down nutrients like slimes, carrion crawlers, and fungi monsters like gas spores and myconids.
  • Level 1 (Producers): Plants and algae make their own food. These include plant monsters like shambling mounds and twig blights.
  • Level 2 (Primary Consumers): Herbivores eat plants. Curiously, there are not a lot of these types of monsters in core D&D. Giant boars, goats, and lizards might qualify.
  • Level 3 (Secondary Consumers): Carnivores that eat herbivores. There predators aplenty, and this is where a lot of humanoid monsters can be found, from kobolds and goblins up to orcs and hobgoblins.
  • Level 4 (Tertiary Consumers): Carnivores that eat other carnivores. The most dangerous of these are apex predators, who have no predators. These are monsters that can challenge entire parties, like dragons and krakens.
Food webs can be incredibly complex, but for a game master's purposes even a simple pyramid can help sketch out what creatures depend on others and the impact of their removal.

An Adventurer's Guide to Subterranean Sustenance​

The anime series Delicious in Dungeon offers a humorous look at a dungeon with an internally consistent ecology. The protagonists frequently consider the ecological implications of their actions, driven by their need to eat the monsters to survive.

A prime example is the episode, "Kelpie/Porridge/Broiled with Sauce." The adventurers observe that a kraken (Tertiary Consumer) has become so successful at hunting the dungeon's mid-level monsters that their populations are dwindling. This leads to fewer food sources for other creatures, highlighting how the removal of too many mid-level prey can negatively impact the entire ecosystem. Similarly, Senshi the culinary dwarf advises the party's spellcaster Marcille to not just blast the flying bladefish (Primary Consumers), because killing too many can lead to the collapse of the ecosystem since they are at the bottom of the food chain.

Another instance is "Stewed Cabbage/Orcs," in which a red dragon's (Tertiary Consumer) presence drives orcs (Secondary Consumers) from their underground villages to raid human settlements on the upper levels. The protagonists initially view taking out the dragon as a purely good act, but Senshi consistently cautions against the unintended consequences of disrupting the natural order. Of primary concern is that each level of monsters keeps the ones below it in check, and that by eliminating any one trophic level, it will cause a surge of monsters to escape the dungeon, thereby terrorizing the populace further. His warnings reinforce the idea that removing too many alpha predators can have potentially harmful effects on the dungeon's delicate balance.

The Ultima Online Cautionary Tale​

A lot of this is just theory; after all, a DM can tweak their world as they see fit. But it has played out in video game ecosystems, most notoriously, the massive multiplayer online role-playing game (MMORPG) Ultima Online. The developers intended to create a dynamic ecosystem with a natural food chain: deer (Primary Consumers) would eat grass (Producers), wolves (Secondary Consumers) would eat deer, and dragons (Tertiary Consumers) would eat wolves. This trophic hierarchy was designed to create a natural flow of resources and creature spawns within the game world. Then adventurers were introduced into the system.

The reality of adventurers (Secondary Consumers) entering the scene quickly collapsed the carefully-crafted system. Player characters, acting as powerful predators themselves, indiscriminately hunted wolves, deer, and rabbits for loot, experience, and resources. There were just too many Secondary Consumers -- and in reality, some of the adventurers as they became powerful enough were Tertiary Consumers -- and they didn't have any inclination to stop. Like hunters depopulating an entire species for pelts, adventurers just did what they did: killed things just because traditionally that's what players did in other MMORPGs to advance in level.

This excessive predation highly unbalanced the system, leading to unnatural population declines. The developers were eventually forced to adjust how creatures fed and thrived to compensate for the players' overwhelming impact.

Bringing Your Dungeon to Life​

For DMs looking to create truly immersive megadungeons, considering the underlying ecology is paramount. By thinking about the food chains, predator-prey relationships, and how the environment sustains its inhabitants, you can craft a dungeon that feels alive and reacts to the players' presence. Similarly, nature-minded PCs might care about this stuff like Senshi does; he frequently admonishes the party's spellcaster to stop obliterating everything on the map out of fear of collapsing the entire ecosystem. Good-aligned PCs who care about the villages above the dungeon may similarly be inclined to try to manage monster resources vs. just wiping out everything that moves.

Just as Delicious in Dungeon illustrates, even adventurers driven by their own needs can become part of this intricate web. And as the Ultima Online example shows, the players themselves can have a profound impact on the dungeon's natural order. So, the next time you're designing a sprawling underground complex, consider taking a page from Senshi's cookbook and give players a reason to think about what the monsters – or the PCs! – eat.
 

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Michael Tresca

Michael Tresca

(long time lurker, first time poster)
I love me a good mega-dungeon, both as a player and a DM
I think It's something to do with you can have all the same kinda story-beats, group/individual relationships/conflicts, etc, all within a very claustrophobic space leading to a certain amount of hyperawareness that I can get my head around
the last game i DM'ed was 'Waterdeep dungeon of the mad mage' with some of the DM's Guild expansion and my own stuff during the pandemic - wish i got to finish that, maybe another day
anyways, just to say nice article, cheers
 

Wise words: "The lesson of the virtuale ecology was to us that testing the game in house is an entirely inadequate test in contrast to the reality of being in the hands of players. Not only are players going to face &think about the experience differently than we do in house but by sheer numbers they will crush or test things in a very different way"

I remember hearing about UO back in the day and immediately thinking about the obvious problems online gaming had displayed by then∆, it's good to hear about how they recognized and tried to address some of them but also realized sometimes intended design can't work in the wild and did what they could to replace it with needed design. Sometimes it seems like there is a trend in modern gaming (ttrpgs especially) for designers/publishers to state the intended results of a design that worked in closed door play and blame anyone who has a bone to pick with the results in actual real world play rather than doing anything about the merits of that bone itself.


∆ UO was starting to compete with EverQuest by then or would soon. That's not a slight against UO though... It nearly predated widespread consumer Internet and very much kicked off online gaming in a format other than text based MUDs. They were building the racecar while the track it worse on was still being paved
 

Wise words: "The lesson of the virtuale ecology was to us that testing the game in house is an entirely inadequate test in contrast to the reality of being in the hands of players. Not only are players going to face &think about the experience differently than we do in house but by sheer numbers they will crush or test things in a very different way"
So fun and weird fact is that there was a MUD discussion mailing list that at the time was the intersection of folks who administrated Multi-User Dungeons (like the game I'm still admin for, RetroMUD) and these up-and-coming MMORPGs like Ultima Online, and the UO developers were on there. We argued. A lot.

Mostly because of exactly this, which was because their wide-eyed "we're gonna make a system that replicates real life and automatically adjusts for population growth" was positioned against our hard-earned experience, that players had been trained to murder everything online whether or not it made sense, and would do so regardless of incentives unless there were hard guardrails to stop them. Clearly, we lost out, and UO had to learn the hard way.

What's worse is this doesn't just apply to monster NPCs, it applies to PC vs. PC, with griefers being their own form of apex predator. I had a stupidly memorable encounter where I got up to eat a sandwich in real life and left my character in a (supposedly safe) room ... and returned to discover a PC thief in the room pickpocketing me. I attacked him ... and guards appeared and began fireballing me into oblivion. Same issue, different (terrible) solution which ended up protecting PC griefers and punishing newbies.

I stopped playing after that.
 

. . . that players had been trained to murder everything online whether or not it made sense . . .
Not sure this problem is limited to the online world.

I'd like to repeat the maxim here, since it relates, paraphrased:

No dungeon survives first contact with players.
 

@unjulation I usually welcome new members to the site, but welcome to un-lurking, de-lurking? I would tend to say something pithy here, but you know how it works by now. Cheers

Creating dungeon ecology can be as real and time consuming as the group wants it. I mean, how many dungeons never include bathrooms, or just throw in a ogyough, oh-my-ga, ogy-bleh to just act as a garbage pit and cube to vacuum up.
 

So fun and weird fact is that there was a MUD discussion mailing list that at the time was the intersection of folks who administrated Multi-User Dungeons (like the game I'm still admin for, RetroMUD) and these up-and-coming MMORPGs like Ultima Online, and the UO developers were on there. We argued. A lot.

Mostly because of exactly this, which was because their wide-eyed "we're gonna make a system that replicates real life and automatically adjusts for population growth" was positioned against our hard-earned experience, that players had been trained to murder everything online whether or not it made sense, and would do so regardless of incentives unless there were hard guardrails to stop them. Clearly, we lost out, and UO had to learn the hard way.

What's worse is this doesn't just apply to monster NPCs, it applies to PC vs. PC, with griefers being their own form of apex predator. I had a stupidly memorable encounter where I got up to eat a sandwich in real life and left my character in a (supposedly safe) room ... and returned to discover a PC thief in the room pickpocketing me. I attacked him ... and guards appeared and began fireballing me into oblivion. Same issue, different (terrible) solution which ended up protecting PC griefers and punishing newbies.

I stopped playing after that.
I wouldn't say that it's exclusively a thing where players are trained to behave a certain way online. The wow blood plague incident may have been amusing AF at the time when merchants were infecting low level players with a lethal plague, but it also provided a ton of great data that was useful for modeling human behavior in a pandemic.

A lot of the time player behavior isn't all that different from when someone decides "what if there were no meaningful consequences" and "what if we just declare that these folks are not a person to me" you can pretty much predict how players will behave by looking to history where one or both of those was true if there is any benefit to a given action. That predictability is why the game needs to include a reason why one or more of those can't be true or the option is somehow walled off.
 

Wish more thought was put into the ecology of Dungeons/ruins/fantasy environments. As a GM I try to build every place to be used again and again. Dungeons that players have killed the BBEG become rental property to any henchmen or lesser monsters in the area, plus every up-and-coming treasure hunter head to it to gather any treasure left behind.

Examples:
  • Bodies not given death rights have a good chance of roaming as undead.
  • Removing of a BBEG creates a power vacuum and something will fill that vacuum. Sometimes this means the true owners want the place back, others just goes back to nature.
  • Location, location, location. Its place is just in the best spot not to be used over and over.
 

Examples:
  • Bodies not given death rights have a good chance of roaming as undead.
  • Removing of a BBEG creates a power vacuum and something will fill that vacuum. Sometimes this means the true owners want the place back, others just goes back to nature.
  • Location, location, location. Its place is just in the best spot not to be used over and over.
I think Cragmaw Castle near Phandalin was home to 6-7 bad guy groups of scum and villainy before the PCs had some henchmen settle there and build a proper road.
 

Don't overlook the impacts that dungeon ecology can have on topside ecology. Real world example would be cave complexes that are home to thousands of bats. The bats eats things topside and then provide food for things inside. Plus sometimes a usable pile of waste for humans needing fertilizer or ingredients for gunpowder.

In a RPG setting, maybe the bats eat things other then small bugs. Perhaps things like stirges. When some band of adventurers come through the dungeon and kill all the swarms of pesky bats(who likes bats?), the top side village humans notice an increase in stirge attacks. If later, the adventurers go to the village to proclaim their successes in clearing the dungeon, they may get a different type of welcome, like winding up in jail and handed a bill for 200 dead cows and sheep that were drained of blood by the now unchecked swarms of stirges.

Also, if the party mangages to bypass most of the smaller inhabitants and kill the top level predator, possible unchecked hordes of lower level pedators will soon be swarming over the countryside looking for food. If the party kills the <big monster>, what keeps the rapidly breeding goblins in check?

A party clearing or partially clearing a dungeon could be a plot hook for involving the party fixing the problems caused by the dungeon clearing.

I liked the "Ecology of" articles in the Dragon magazine. Our games rarely lasted longed enough per campaign that dungeon ecology was a concern, but still fun to keep in mind.
 

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