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