The underworld and shaft digging
Below the surface, paths are not merely revealed; they must actually be cut from the rock.
Each burrow has its own passable grid of chambers and passages. A slime moves tile by tile there too and can navigate only through excavated ground. Shafts, portals and exits are fixed passages between particular worlds.
Digging costs energy. Work pauses if the next tile would demand more strength than remains, then resumes after sufficient rest. Portals, the map edge and the ceiling near the surface remain protected. Autonomous building and direct digging orders use the same physical underworld but follow different decisions.
Not every change below ground comes from a colony. Physical digging creates lasting passages. If a vein is exposed, its contents initially remain in the ground; supplies directly run over may instead be lost. Existing connections are not removed by these passages.
Cracked earth
Some patches of earth are laced with fine cracks. The ground there is loose: once such a spot is dug into, it gives way, and the loose earth caves in ring after ring into a chamber within a moment. Usually the whole chamber opens; now and then a wall stays standing and gives way in turn when it is dug again. Some of the cracked patches lie in noticeably darker earth.
Whatever lay in such a chamber becomes reachable only once it breaks open. Some are empty, others hold food or nectar, which then lies in the burrow like any other parcel. And not every chamber is uninhabited.
Colonies digging their passages on their own pay no heed to cracks; whatever they uncover, they come across along the way.
Stores and nectar
Food and nectar parcels lie as real objects on free ground tiles. Nectar parcels mature in the forest's shared underworld; crystal deposits can be both a resource and a digging target. A distant parcel counts for a queen only if it lies within her local supply area.
Glowing objects can be picked up like stones and carried; they take the same place as a food parcel. While carried and after being set down they keep their night light, on the surface as well.
Foreign glowing objects can injure Gloom with light at night, even in their own burrow. Lights native to Gloom's biome and the forest's glowing objects remain harmless, including when carried elsewhere. When a carrier dies, its glowing object falls to the ground and continues to shine.
Sight without surface fog
There is no broad fog-of-war mask underground as there is above. Other creatures, portals and objects are discovered for the Bestiarium through local proximity, not merely because they exist in a generated burrow.
