I've come up with an explanation for how the game world works, or at least how part of it works.
In Dungeon World, the monsters are magical creatures. There's a fair amount of loose magic floating around, enough to sustain the creatures, so they can exist perfectly fine just wandering around loose, which is their natural state. They also eat normal food, with most magical creatures having a particular fondness for rat.
In Dungeon World, there are also wizards. Through intense study, wizards have learned how to tap into that ambient magic and use it to produce incredible effects, often amassing great power for themselves along the way.
Eons ago, one of the most powerful wizards ever to live discovered that a very small portion of the population had an innate ability to absorb, concentrate, refine, and channel magic. Some of the individuals with that gift became wizards, their power subtly boosted by their natural talents, while most went about their lives blissfully unaware of their potential. This ancient wizard, Sheifan, was one of the gifted, and discovered that with the proper ritual, he could channel some of his power to magical minions, greatly increasing their power and resiliency. He raised an army, marched on the civilised nations, and was crushed brutally when he forgot to bring enough food for his minions and they deserted him. They carried with them the recipe for the ritual of binding, and now most monster tribes have at least one wise old monster who knows how to perform the ritual.
Monsters benefit greatly from association with a Channeler. With the refined magical power supplied by their liege, monsters are able to learn much more quickly, and steadily develop their powers. Many of them grow steadily stronger, faster, and smarter as time passes, and virtually all monsters gain new abilities with continued service to a powerful lord. Most importantly, while a normal monster can be disrupted and even killed, a monster linked to a Channeler has a constant stream of magic coming in to keep them healed. The end result is that a monster serving a Channeler can be knocked down any number of times but never completely killed until the Channeler is killed.
Channelers, in turn, gain virtually nothing from acting as living power sources. They gain no abilities and no powers, although they also aren't weakened by the process. This makes it a pretty one-sided deal, so to convince Channelers to feed them power, monsters offer to serve Channelers and obey their every order... when it's reasonably convenient to do so, and as long as they're well paid and well fed.
The life of a Channeler is often difficult.
Now, in terms of gameplay, what all this means is that you're going to have a couple different resources to manage. The first is food -- if you don't have enough food (which is to say, a steady stream of rats) you can't feed your minions, and they'll get unhappy and eventually desert you. Before a monster agrees to work for you, they'll check out the food situation, so you can't even hire a monster unless you're producing enough rats to feed your existing minions plus the new one.
The second is gold. Gold is required in order to pay your monsters, buy them gear, and buy ritual components so you can perform a ritual and bind the monster's essence to you.
The third is mana. For now, there won't be any player spellcasting in the game, but I'm thinking of a few mechanics that would allow you to tap your mana pool to improve some aspect of your dungeon's functioning (accelerated building, increased gold production, zones of improved combat effectiveness, that sort of thing). But mana is also used to feed your monsters. More powerful monsters require more mana to sustain them, and as with food, if you don't have enough, monsters won't sign on with you in the first place.
Acquiring rats will be fairly easy, I think. I'll probably set up rat farms as a furniture item your monsters can build, with each rat farm supplying a steady stream of 1 rat per turn or something to that effect. Fighting adjacent to a rat farm will likely create a small chance of breaking the rat farm, giving your minions reasons to protect the farms and put them in out-of-the-way places.
Gold is also likely to be pretty simple to acquire. I'll most likely go with something as basic as gaining gold by looting the bodies of your fallen enemies, although the monster who delivers the killing blow will likely get to keep a percentage of the gold.
Mana is a little trickier. I was thinking of having it generated by creatures, but then it just amplifies itself and having lots of mana causes you to have even more mana. Instead, I'm considering some variant where it's based on the size of your dungeon. But then I need to create some sort of balance so you can't just dig out a massive, sprawling, mostly-empty dungeon and gain crazy amounts of mana while you've only got a couple kobolds kicking around. It's gotta be tricky to maintain. One possibility I've been considering is that your dungeon might need maintenance, and every bit of work your monsters do costs you gold, and maintaining your dungeon in an orderly state - necessary for mana generation - costs gold. Higher-grade dungeon areas (polished marble floors instead of dirt, for example) cost more to maintain, but attract a higher grade of monster and also provide more mana.
So, anyone have any thoughts on the topic?