Reefer: Cold Chain
Cold here is not a state but an expense. The compressor holds the setpoint as long as it has power, and every open door pushes back into the box exactly as much warm air as there is goods standing in the doorway.
The body is split into zones: meat, fish, dairy. The setpoints differ and they argue — a deep freeze for the fish steals warmth from the dairy, and a single compromise setpoint, good enough for everyone, writes off both batches at once. The player chooses the layout before departure, then only pays for it at each stop.
A stop is a door. While the cargo is out, the temperature climbs, and it climbs faster if the unloading is slow. Standing still is not allowed either: the receiving window is scheduled. You may kill the engine during a long wait and save diesel — the compressor stops, and a zone crosses its write-off threshold before the unloading even begins.
The run counts delivered batches, batches written off on temperature, and fines for missed windows. The debrief annotates each zone: which unloading let the heat in, how many degrees each door cost, and where saving on fuel ate the entire margin.