Harder Underground adds some more advanced block falling physics, making stone unable to "float" without support. The sections below detail how each block behaves, which can be visualized in-game using the Mohr's Goggles.
Stone Types[]
Various fractured stone types
Currently the following stone types are converted to "unstable" forms:
- Vanilla stone
- Gany's Surface 1.8 stones
- See also: Gany Integration
- Et Futurum
Planned support:
- Geologica
- Requires an API to properly support the planned future tech tree. Postponed for now.
- Geostrata
- Requires untangling Reika's class structure to figure out what the blocks are.
Unable to support:
- Underground Biomes's block placement happens after COG, thus I am unable to detect it.
Smooth Stone[]
Smooth stone can support itself out to 5 blocks (shortest orthogonal distance) as shown at the right. The block above the red wool doesn't fall (supported from below by a block with a solid top face) but does when the wool is removed, as the adjacent white wool does not provide support and the stone is 6 blocks away from the nearest valid support. Any block 1 down that is smooth stone, has a solid top surface, or is-full-opaque-cube will count as support. It is assumed that that block is either self-supporting (all non-gravity affected blocks) or is already supported in this manner. In that way, arches and vaulted ceilings can be created to cover large open spaces without the need for support columns.
When unsupported, the block turns into unstable cobblestone and collapses, damaging its neighbors (which is why there are two collapsed blocks in the picture at the right).
Fractured Stone[]
Fractured stone is stone that has been slightly damaged in some way, either by a collapse or from an explosion. Fractured stone can either be supported from below by any block with a solid top face or by a horizontally adjacent smooth stone (fractured and the other damaged blocks will not support the fractured block).
Damaged Stone[]
Damaged stone is heavily damaged, it has taken multiple hits from collapses or explosions, and as such can only be supported from directly below by a block with a solid top face, by two orthogonally diagonal-below blocks (that is, 1 below and either 1 to the North, South, East, or West, but not North-West) with a solid top face, or four such blocks diagonally below in any cardinal direction (N, E, SW, etc.)
Cobblestone[]
This is the most damaged state of stone and can't be supported at all over open space, and in fact, will fall "sideways" if possible, forming a rough pyramid instead of stacking up like vanilla sand and gravel. Sand and gravel are similarly modified. Note that this can cause some of the falling blocks to drop as items, as two blocks end up popping into the same space.
Mining any form of unstable stone will drop the unstable cobblestone variant, which smelts back into the unstable stone block. All unstable cobblestone is registered in the ore dictionary as "cobblestone" and thus valid in all cobblestone ore-dict recipes. In order to get the vanilla smooth and cobble stone, surround the unstable cobble with sticks in the crafting bench. This will yield the stable, vanilla cobble which can be smelted back into smooth stone as normal.
Be aware that vanilla stone can still take damage from collapses and explosions (see below), rendering it unstable again.
TNT[]
TNT explosions are much more interesting with unstable blocks than vanilla stone. When an unstable stone block is destroyed by an explosion, there's a chain reaction as fractures rip through the surrounding blocks, damaging them. These fracture lines will always tend extend outward away from the center of the explosion and travel up to 13 blocks.