Level one is coming along. There was this moment today, when I first started filling the map I've been working on, when I just didn't know what to put down, but once I started working on it ideas flowed a lot easier. Even if it was just stuff like "this room fills with poison gas," getting something down got me thinking of more interesting things as I went.
This level doesn't have a whole lot of active interference by the fortress mind. It's largely not hooked up to the main machinery of the deeper levels, and what is here is relatively simple, since it wasn't intended for much more than harassing travelers in the first place. That goal has mutated over the centuries: now, instead of keeping people out, the fortress tries to lure them towards the deeper levels. But it does that mostly with occasionally changing inscriptions on the walls, one-way doors, and simple traps, and there are places in the level where the brave and the lucky can tinker with its workings.
The main goal I have with this level, beyond getting the hang of dungeon design myself, is to introduce a lot of ideas that I want to use in more complex form either deeper into the first level itself, or on level two. Some of this is puzzle related -- rooms divided by walls of force, but where there's a fairly simple detour to the other side, so the PCs will get the idea when they discover similar, but much more difficult set-ups. But mostly it's thematic stuff: Ranines in one room and giant porcupines in stables the next room over, the tiny robots that do (among other things) dungeon maintenance, messages from the dungeon itself.
Mostly, I want to give the sense that there's a lot going on in this place, and that there are things to figure out. My earlier attempts at dungeoneering suffered greatly for the lack of that sense, and some of my potential players are suspicious of the idea of megadungeons (I suspect) because they don't think of the things in those terms. This dungeon is a learning experience for me, but it's also going to be a learning experience for whoever runs through it; none of my gaming buddies have had much more experience than I have with megadungeons, or dungeons generally. So I'm keeping that in mind.