oh by all means I'm not necessarily looking for a true to life model lol, I can build a dirt block into the sky and mine platinum without a care in the world lol, I'm focusing on the aspect of it not acting strictly like water, not really vouching for complications
As much as this would make the game more interesting, if added I reckon the FPS will take a serious hit.
The FPS hit wouldn't be too bad if you treated heat pretty much like a light source (hey, heat kind of IS a light source!). The major difference is with the opacity, I.E. where it can extend and where it can't.
I like the idea of a fully functioning fluid system for oxygen and would support it, assuming the increase in fluid computations doesn't cause too much lag. I disagree with the "smoke" fluid idea. I think heat should use a model that approximates real heating and cooling. I don't think FPS would be an issue. Determining the amount of heat in a room is a simple calculation that only needs to be done when rooms are created or destroyed. The biggest computational expense would be efficiently determining when rooms are created, but other games (Terraria, Craft the Earth) already do this. You shouldn't see any FPS drop when, for example, entering or leaving a room. Another difference is that the magnitude of light decreases with distance. The model in the first post assumes the same amount of energy everywhere in the room. I should add that it would still be hottest immediately adjacent to a fire, like it is now; but everywhere outside its immediate range would be the same smaller temperature.
This is something I think is really needed... One of my characters has a not-very-large cottage, with just enough room for every crafting table... The planet gets cold at night, and I don't want to put campfires everywhere in the house to keep it warm... On that note, being in bed should very slowly warm you.
Honestly I wouldn't be surprised to see this implemented. There are a multitude of threads about exactly this. We already have zones where gravity differs from the rest of the planet, so why not heat too. I do not know what the code looks like, but it shouldn't be that much of a stretch from zoned gravity to zoned heat.