For one, the areas are designed and partially inspired by Midas magic and PJs spells. Also, idk if you saw but the synth had key + key = key to hidden room. Well, i think this settles what the hidden room will be about =D. Also, a Nexus is a series of connected groups...so maybe a slight modification to the design could make this a reality.
EDIT: Little update: I added a couple of rooms. Shouldn't be too hard for me to make up since they're inside and not scripted. I have designed the overall story for how you get this house and why it exists and I'm working on setting up all the necessary lines for every character. Looks like there are 6 major characters, 1 minor and 1 super minor. Five of the characters will work in the house, one helps you find it, one starts the quest and one is the antagonist (the previous owner).