Below the surface of the planet there are several layers of complexity that serve various functional purposes, additionally within each of these layers there are zones that serve as gateways which both connect and limit traffic between the layers.

The lowest layer is polyandria which is really just an even older catacomb. The layers above it all fall loosely into the undermetto. The zones that connect these two layers are the clockwork catacomb; so named because they constitute an elaborate mechanical puzzle.

It's important to note that the clockwork catacomb is not just one, but several areas that are all connected via a network of bridges, doors and other means of passage, all located on the same transitory layer. Additionally if one is to successfully transverse the clockwork catacomb it is necessary to activate each passage in sequence.

While primarily passive, the catacomb is not exactly user-friendly, nor is it a walk the park. It does have its fair share of perils, manly due to the mechanical nature of all the mechanisms, most of which are at an industrial scale. Many hapless explorers are crushed in giant gears or fall into bottomless shafts while attempting to traverse a particularly challenging impasse.

However once the explorer has passed the many challenges they gain access to the polyandria, the resting place of the ancient gods. And if they continue to go even deeper they may even reach the diamond fortress a.k.a. crystal fortress.