Reshaping the world

Discrete conserved substrate, not unrestricted voxel physics. Every location has a shallow column of ground that organisms can excavate, carry and deposit - and every organism has the sensory channels to perceive what that actually does.

Three layers, one column

Every world cell has a bounded vertical substrate column made of three things, stacked:

• Immutable base geology - the elevation the world was generated with. It is never rewritten by anything organisms do.
• Movable substrate - a conserved, signed count of substrate units piled on top of that geology or cut away from it. This is the one layer organisms can change.
• Ecological cover - how much of a cell's living, mature ecology is currently expressed. Separate from the physical shape beneath it; see ecological succession below.

Terrain geometry and ecological surface cover are two different concepts tracked separately. A cell can be physically exactly where an organism left it while looking, ecologically, almost nothing like the moment it was disturbed.

Excavate, carry, deposit

The whole mechanism is one small loop, using the same two manipulation channels every organism already had:

1. Excavate - pull a unit of substrate out of the cell directly ahead, if it is exposed above the waterline and has not already been dug to bedrock.
2. Carry - hold that unit while walking. Carrying costs a little extra to move.
3. Deposit - put the unit down, either onto the cell ahead or onto the organism's own cell.

Building somewhere requires taking material from somewhere else.

Matter is conserved exactly: the total substrate sitting in the ground plus the total substrate every organism is currently carrying never changes, whatever combination of digging and filling happens. A quantum that appears somewhere was taken from somewhere else, always - even an organism that dies mid-carry deposits its load back into the ground rather than deleting it.

What this can actually do to the map

Columns can rise or fall. A cell dug down enough crosses the waterline and becomes submerged; a submerged cell filled in enough becomes dry land. Shorelines can move as a direct consequence. Given enough conserved material and enough time, the map is not fixed at genesis - it is a record of everything that has happened to it since.

No build action, no construction reward

There is no channel an organism can raise to say "build here", and nothing in the energy model rewards a filled channel, a raised terrace or any other shape more than an unmodified one. Excavating and depositing cost energy like any other attempt, whether or not they succeed. Whatever an organism does with this affordance is a side effect of ordinary survival pressure, not an instruction it was given. We are watching for whether evolution discovers useful environmental modification at all - not assuming it will.

Organisms can perceive what they are doing

An earlier experimental predecessor (Phase Y, using a continuous heightmap rather than discrete units) let organisms modify terrain without giving them enough information to learn its consequences, and both live candidates went extinct of starvation within a few thousand ticks with the terrain change itself not clearly implicated either way. The current architecture closes that loop: five observation channels (of 53 total) report the substrate directly - whether the organism is carrying a unit, how built-up or dug-out its own cell is, whether the cell ahead steps up or down, how much material that cell could still give, and how much it would still need to reach the waterline. See the substrate channel group for the exact channels and ranges.

Still a 2D world with vertical columns, not 3D voxels

It is worth being precise about what this is not. There is no roof, no room, no arbitrary stacking of interiors, and no navigation along a third spatial axis. An organism occupies one (x, y) cell; the column at that cell has a height, and that height affects passability and the waterline, but organisms do not walk under, over or through one another's columns in a literal 3D sense. This is a 2.5D discrete substrate system, not Minecraft-style unrestricted voxel physics.

Disturbed ground is not a permanent scar

Digging or filling a cell disturbs its ecological cover - it does not touch the physical shape underneath. A heavily worked cell can, for a time, look bare and disturbed. Left alone, and if current conditions actually support it, that cover recovers over time toward whatever the cell's present physical state and moisture would naturally mature into - not necessarily what was there before it was dug. A former seabed cell that has been filled in and left alone can, in principle, mature into grassland or forest on its own physical merits.

The physical terrain shape an organism leaves behind can be inherited by the world going forward. The ecological appearance recovers on its own separate timescale. A terrace or a filled channel dug by organisms many generations ago might, by the time you look at it, be indistinguishable by eye from ground that was never touched - even though the world's own history still records what happened there. This does not mean anything has engineered a landscape on purpose; it means the world no longer punishes physical change with permanent ecological damage.

What has actually been observed

In the staging world that preceded Universe 1, land area had increased by roughly 3% from that world's genesis, and significant portions of the map had been physically reworked. That was the first evidence of real, persistent terrain modification under evolved, unscripted behaviour.

Universe 1 has since gone very much further. Measured on 3 October 2026, at tick 897,930: land area up 14% from genesis, roughly 45,000 units of substrate stripped out of the two islands' interiors and piled into the southern ocean margin, a third of the original land dug to the excavation floor, and about one cell in five of it dug so far that it is below the waterline and cannot be walked on at all. The built ground now spans the full width of the world's southern edge, and it carries the only route between the two landmasses the generator kept apart - remove the cells that are walkable only because material was put there, and the world falls into two pieces again.

That is a change of map topology produced by a population that has no build action, no plan and no reward for height, and it should not be read as construction, engineering or intent. The section above on the absence of a build action is the part that makes it interesting. The strait that closed is the full account with the measurements and the pictures; the research notes carry the unvarnished experimental history, including the predecessors that did not work.