Temperature

Temperature is the warmth of the ground a cell stands on, read from -6°C to 150°C. Every cell carries a temperature tolerance gene holding the temperature it prefers and how wide a band around it is safe. Outside that band the cell leaks cytosol, and the heat side costs far more than the cold. Below a cold floor and above a heat ceiling it dies outright. Cells make heat as they feed, so the temperature that kills a culture is often one the culture made.

Cold floor and heat ceiling

Ground at or past either line kills a cell in the frame the value is read, whatever its genome, and nothing in a genome moves the two lines. Between them temperature is a drain, not an execution. pH has no equivalent lines: it drains, and never kills in one frame. Cells stopping all at once instead of thinning indicates ground past one of the two lines.

A cell that runs out of cytosol is labelled by whichever damage source dominated the run-up. Temperature keeps one signed accumulator for both poles, so a slow freeze reports froze and a slow cook overheated, the same labels the instant deaths carry. A cell past mid-senescence reports old age ahead of either, and a death with no dominant source reports as starvation.

Temperature tolerance gene

Every cell has exactly one: mutation can neither delete it nor add a second. It holds two numbers.

• Optimum, the temperature the cell prefers, which mutation clamps to roughly 0°C at the cold end and 134°C at the hot end. Above about 103°C the gene halves the heat half of its own band. The heat ceiling sits below that point, so the halving shows in the readouts and in what a dose measures against, rather than in damage.
• Width multiplier, 0.3 to 2.5, scaling both halves of the band. Below 1.0 the band narrows. Above 1.0 the sim charges a residual drain, zero at the cell’s own optimum and at full rate at the band edge. 1.0 is the only width that takes the full base band with no residual.

Cold damage ramps as the square of the excess past the band, capped at 2x; heat ramps as the cube, capped at 3x. Either drain scales with the cell’s cytosol capacity and its membrane permeability.

Stress costs twice, on either side of the band. A stressed cell’s mitochondria fade toward a floor multiplier on cytosol gain while its consumption is not throttled, so it keeps pulling nutrients and wasting them. Lost income, not the drain, is usually what empties the pool.

Colony heat

Metabolic work deposits heat into the substrate field around each cell, and it diffuses and decays back toward the culture’s ambient setting. A cluster holds a warmer patch than the dish would carry; losing cells drops the patch, and more cells cross the floor.

Heat scales with the cytosol produced, superlinearly with mitochondrial efficiency, and with the cell’s own optimum, so a thermophile warms its ground most and a cold-adapted lineage least. A nucleus at the mitosis threshold adds more. Pseudopods and slime-mold networks spread the same total heat over a wider footprint, lowering the peak at the body without lowering the sum. Losing every mitochondrion is no exit: the fermentation path emits waste heat at a raised rate per unit of growth.

A mitochondrion gene carries a rare toggle, the cryochondrion, that inverts that organelle’s heat output, so a cell holding a mix heats and cools at once.

Past a small deadband, hot ground pushes the fluid outward and cold ground draws it in.

Crystals and compounds

Exothermic crystals drive the channel to the top of the scale and endothermic ones to the bottom, which is below the cold floor. A crystal placed in play sheds drifting molecules, so its aura travels on the current and reaches past its body: chilling a rival’s ground kills player-owned cells inside it. Removing one by hand snaps its aura back to ambient; letting it dissolve leaves the temperature behind.

Two compound rows drive the channel deliberately, Thermogen and Cryogen, and Cryogen also arms the cryochondrion switch.

Adapting to the ground

Every division steps the optimum toward the temperature at the point of division. The weighting runs from 3:1 at the edge of the deadzone up to 8:1, with steps that go with the ground enlarged as well, so the further the ground sits from the reference the harder it pulls. That reference is 37°C, not the cell’s own optimum: within roughly 8°C of 37°C nothing is aimed at all, and on colder ground every division is pushed downward wherever the optimum already sits. Extreme temperature also raises how large and how often mutations land across the genome.

Double-clicking a cell’s nucleus buys a paid dose, which aims the drift. A dose closes 21.6% to 38.5% of the remaining gap to the local temperature per dosed division, four to eight divisions to arrive. On ground whose spread is wider than the narrower half of the band it widens the band instead. One or the other, never both.

Past a stress threshold a motile cell flees down the gradient of its own thermal stress, at a survival floor plus its evolved flee response. The response is clamped non-negative, so a lineage can evolve stoicism but never attraction to the stress.

Contaminants and seeded rivals arrive retargeted onto the dish’s ambient, band width pinned back to the default rather than whatever their spawn mutations rolled.

Climates and board nodes

A culture climate is a centre and a spread: the centre is both the average of the generated field and the value it decays back toward. Six presets exist: TEMPERATE, COLD, GLACIAL, HOT, THERMAL and VARIABLE, of which only TEMPERATE is ungated. GLACIAL makes the coldest ground of the six; VARIABLE keeps the temperate average with the widest spread on offer, so its cold veins run colder than COLD’s on a dish whose headline reads temperate. No preset reaches the floor.

Board nodes do. A node’s ambient is rolled from a range reaching far below anything the presets offer, and its spread with it. A node’s dish also carries a cold pole, a fixed bearing along which the ground cools from the dish’s centre out to its rim, stronger the further out the node sits on the board. The pole is capped at the headroom above a fixed node floor, so a node already at that floor gets none, though its own terrain spread still carries ground below it. The board’s strain readout tests both axes against every deployable strain, and temperature alone can put a node out of reach.

Contracts ask for thermophiles and psychrophiles by optimum against 37°C, and the exchange pays for a far optimum held in a narrow band.