To be clear, even after King Dugan’s Dungeon establishes the pattern of theme levels, not every level is a theme level. There are still a few variety levels, where each room does something completely different. But on the levels where it goes for a theme, it goes hard. I’ve just been through a very strong example of this: floor 20, where the game introduces Brains.
I’ve mentioned Brains before. Brains don’t attack you directly, but rather, make all the other monsters on the level a little smarter, giving them access to a simple pathing algorithm that tells them how to get aorund obstacles without getting stuck. Intriguingly, it seems like Brains don’t so much tell the monsters what to do as give them a better perspective on the world. Ordinarily, roaches try to get as close to you as possible, roach queens try to get as far away from you as possible, goblins try to avoid your sword and charge you from the back or side, wraithwings try to stay 5 squares away from you until they can mob you in a group. Brains change none of this. They just change how the monsters assess distance. Without a Brain, roach queens tend to get stuck in corners, where there’s only 3 empty adjacent tiles to spawn new roaches in. With a Brain, you can wind up chasing a queen around a loop if you’re not careful. Serpents seem to be a special case, or perhaps just expose a little more of the general case than the other monsters. Ordinarily, a serpent will make a beeline for you if you’re directly in line with its head horizontally or vertically, and otherwise wiggle around according to a set of rules too complicated to describe here. Add a Brain, and the serpent seems to regard you as always directly in line with its head, and will head towards you according to the same distance rules as everything else.
The main effect of Brains is to erase some of your most useful tactics. You can’t just get a pile of roaches stuck behind a wall where you don’t have to worry about them immediately. Everything that’s awake and not completely isolated knows how to find you. Instead, your movements have to be geared towards making sure you don’t have to fend off monsters from multiple directions at once. If you can get them all lined up in front of you in a hallway, it’s really no worse than normal. In fact, the Brain can make things easier at that point, by guiding all the monsters to you so you don’t have to hunt them down.
In fact, there’s one puzzle where this is completely necessary: in one part of the room, there’s a roach in a sort of labyrinth where every passable tile is a trap door. You can’t go into this labyrinth, because the trap doors would collapse behind you and you’d have no way out, and it’s set up to be impossible to lead the roach out by the normal roach movement rules. No, you just have to wait for the Brain in the room to guide it out, which means refraining from killing the Brain. It’s kind of like refraining from killing the tar mother in that room I described in my last post. Come to think of it, we can probably generalize this to a pattern: situational advantages of things normally regarded as enemies or obstacles. There’s a whole floor devoted to using goblins to kill serpents. Even the humble roach can be used as an obstacle to keep wraithwings from fleeing out of sword-range. It strikes me that one of the big strengths of the DROD ruleset is that it’s rich enough to support situations like this. Everything has some potential use.