I've created a model to explain suggestion for non-linear vertical dungeon design.
Intention of the level is that player have fun exploring because level itself is cloaked with mystery.
Map legend - Sphere - point where engine seamlessly loads upper floor/level and indicates where player can go back down.
These are usually stairs.
- Icosphere - secret item/weapon ... which can be obtained solving the puzzle or is hidden behind secret wall
- Torus - mysterius portal; some are working, some are not
- Pyramid - quest and/or boss area with boss encounter or some other tough A.I.
notes: Walls and pillars are not scaled to exact measure.
They need to be placed to hide some A.I. encounter or secret door to another area
edit: updated