In Oxygen not Included different areas have different temperatures, and you can create and move heat around.
What I have not been able to figure out is whether this is a closed system or not.
Does heat leak in or out from the third dimension? If I stop adding heat to a cold biome, will it eventually re-freeze? If all my duplicants died and the game ran on for ten hours with nothing running, would the starting zone return to 23C?