Heat transfer · mechanic

definition

Each cell, room, or object holds a temperature and often mass, specific heat capacity, and thermal conductivity. Each tick heat flows between neighbors in proportion to the temperature difference and a conductance from both materials, and temperature changes by heat divided by mass times heat capacity. Thresholds trigger melting, boiling, freezing, damage, and effects on agents. In Oxygen Not Included a tick is 0.2 s; cell-to-cell transfer uses q = dT x dt x k x 1000, multiplied by 25 between solids and gases and 625 between liquids; transfer stops below a 1 C difference or 0.1 DTU, and one tick may close at most a quarter of the difference. Insulated tiles divide conductivity heavily. RimWorld holds one temperature per room that equalizes with outdoors through walls and doors and is driven by heaters and coolers.

player experience

Thermal engineering. Players insulate, vent, and cool, and they watch overlays for creeping heat. Late failures arrive slowly: a base heats a fraction of a degree per cycle until crops die or machines stop.

design levers

per-material specific heat capacity and conductivity
phase-change temperatures and their consequences
transfer multipliers between solids, liquids, and gases
tick length and per-tick caps for stability
insulation strength and environmental heat sinks
damage and agent thresholds

failure modes

Rounding and phase-change edge cases let players create or delete heat, which becomes a standard exploit.
Per-cell diffusion across a large map becomes a late-game performance cost.
Without overlays, rising temperature is invisible until a threshold fails.
If equilibrium takes far longer than a session, heat stops mattering; if it is fast, it becomes noise.

dynamics

Machines emit heat as a byproduct, so a growing industrial base slowly overheats itself.
Seasons, fire, and magma couple to temperature and drive phase changes and evacuations.
Heat moved by fluids links plumbing layout to thermal management.