Since the game's release, the fire system hasn't gotten much of a change. Only slight nerfs here and there. I suggest a new system entirely.
Fire Lighting & Maintenance
I think it's a bit ridiculous that I'm able to light a fire with a log and a match alone. I know this is just a game, but it's a realistic one and I think one of it's core systems should reflect that. When lighting fires, regardless of skill level, you should require tinder and small fuel sources.
Lighting the fire will now be interactive as opposed to a meter. You start by making the fire frame. Rocks will be auto added to not make cooking tedious grind for stones. But the rest of the frame depends on what fuel source you're using. 10 sticks is enough to light the fire. Then you'll need a few tinder items. Level 1 fire starting requires 2-4 tinder items. Additionally, you could use a single book as tinder OR rip paper from it to use. Stacks of paper, newsprint, paper gathered from the ground (yes, cleaning up the Camp Office should be a thing too), pamphlets, notes, etc... can all be used. Once you've set up the fire frame, you can strike the match.
Once the fire is lighting, you can add kindling to it. Kindling are things like pine needles (found around the base of trees), shreds of paper, cardboard bits, tinder items, cloth strips, etc... These help the fire get lit. You can blow on the fire to facilitate this process and speed it up. Skill level determines how quickly this occurs, how much kindling and tinder you need, etc...
Once the fire is a small flame, you can begin to add things like sticks, books, larger tinder items like full stacks of paper, reclaimed wood, etc... to it. However it won't instantly be a roaring fire. It will take time for the fuel to catch. But once it does, the temperature will soar up and you'll have a solid fire. After that, you can then add larger pieces of wood to it. Depending on skill level and the size of the fire (fire pit, stove, forge belly, etc...) you'll be able to add only a certain amount of wood before it's full and you need to wait for it to burn into charcoal. While your fire is going, you'll need to maintain it. Obviously adding fuel if it's going out. But also removing fuel if there's too much.
Obviously with a fire that takes time to warm up, it will make no sense to have food instantly begin cooking on a cold surface. You'll need to wait for the fire to reach and optimal temperature to begin cooking food. The fire's temperature also impacts how long it takes to cook, melt or boil food and water. Additionally, if the fire goes out or the item isn't cooked in time, it will maintain it's cooked level the next time you put it on the burner.
Wind, snowfall and cold temperatures can also affect how quickly your food cooks. Especially if it's left out on the hot stones of a campfire pit. (that makes sense right?)
While we're at it, why don't I suggest the ability to move pots and cans containing food or water to other surfaces instead of immediately collecting the item. For realism's sake.
With campfires taking longer to build, it would make sense that players would build them to last long. We've all had those annoying moments when we have a nice 5 hour long fire blazing, our meat is cooking and suddenly the wind blows us the wrong way and... oops... 9 minutes remaining on our fire. This is incredibly annoying and while this will still be able to happen with this new system, I propose a way to prevent it.
Lean-To's! Lean-to's are small shelter's built to block wind and flying debris. Usually they are larger in size, but smaller ones can be built for campfire pits. Something like this. Of course, larger ones like this are also feasible but I think the other one works better. It would only take a few sticks and a log to build. It would protect the fire from any changing wind and you'd be able to move it's position at any time. It would have durability and slowly burn away over time, eventually adding 15 minutes to the fire when it collapses into the flames.
If your fire does go out though, fear not. You can still collect the remaining wood you put in since it didn't burn yet.
A cooking tripod might be a bit too much for gameplay balance, but something like this could be set up over a fire pit to hang a pot for cooking. Or maybe a grill could be placed over it instead. But this isn't something necessary to cook food, just a thought.
I've always found it odd how we can have a fire going all day inside of a cabin and yet when it goes out the cabin is back to -1 degrees. I think that indoors, temperature should be dynamic.
Small, well-insulated shelters should retain heat from fires for longer. Places like the Camp Office, Trapper's, Quonset Garage, Coastal Houses, Lighthouse, etc... are all small enough to retain heat from a fire. Depending on how long and hot the fire was, the more heat will be retained and the longer it will last after the fire has gone out. Larger buildings will not retain heat. Places like the Dam, Hibernia, Last Resort, Farmhouse, etc... are all too large and poorly insulated for that.
The outside temperature will also have an effect on the interior temperature. In a blizzard, small poorly insulated shelters will become colder. Shelters that have heat retained will lose temperature faster than without cold outdoor temperatures.
The aurora being active can turn on most electronics should charged ions in the air, meaning electronic heaters will also be powered on. I would assume that buildings without fireplaces or stoves on Great Bear were powered by electric heating somehow during the cold seasons. So if heaters are powered during the aurora, some buildings can be warmed up but not by much. Cars will also have this effect, but they lose that retained heat quickly. Also, fires outside cars shouldn't be able to warm you up on the inside unless they're hot enough to melt the doors off... just makes sense to me.
Finally I'd like to suggest wax candles as an item you can find and perhaps craft in the world. You would be able to place them anywhere in interior locations. Bonus points if you find a candle holder to carry it around as a light source. When lit, they provide a 2 degree warmth bonus and a significant amount of light. Any small amount of wind will blow it right out, even calm wind. They'll have a durability which lasts a while but once they're out, they're out. The wick can also have a chance of burning out before the wax is consumed and then the candle is ruined. They make for a good light source in interiors at night when you don't want to use any of your handheld light sources. They'll also allow for completing actions in would-be dark locations.
Interior Window Lighting
While I'm at it I might as well point out that interior lighting makes absolutely no sense. Not that it's incredibly dark, but that's in some places it's way too BRIGHT. I'm talking about the dam of course. Somehow the lower dam is pitch black at night but light enough to see during the day despite there being no windows around whatsoever. Make the interior lighting dynamic. This is one of the most non-immersive things I find with the game.
On top of that, windows don't properly reflect the light outside. Sunsets and sunrises should come through the windows as they look outside. During blizzards, it should look like a blizzard. During fog, it should be clear it's foggy. Cloudy outside? Less light coming through. Big blizzard just blow through? Snow on the windows (maybe you can clean it off?).
Looking indoors should be changed too. At night, Trapper's Cabin lights up despite there being no fire burning in there. Change this, make it so that any building with a light source going in it will reflect that on the outside. Whether it be a fire, lantern, candle, flare, torch, flashlight, aurora powered lights, etc...
I know a lot of this seems unnecessarily realistic and nitpicky. But it's my humble opinion that immersion is what makes this game great. All the little details in the environment help make it feel more alive. And small changes like these to gameplay systems I believe make a larger difference when they come together.
I believe these changes will inspire new ways to play the game. No longer will players be lighting campfires everywhere, now it will take longer so they'll have to strategically think of if it's a good idea to light one up or not. It will take a lot of future planning to keep a fire going in the long term, but if you do you'll be rewarded with a warm shelter to return to. This way, players can light fires indoors and go out exploring and then come back to a fire still lit waiting for them. They'll have to think about which shelters are actually viable to stay in, or if they'll be too cold. Now, players will be able to make better use of the aurora and with electric powered heating, exploring new locations during the flare-ups will be easier and more inviting.
I can see how this may seem restricting to some players who prefer the current simplicity of not having these system changes. But the main point I am trying to raise by suggesting this, is that immersive realistic gameplay systems is what makes the game great. And more of them would only improve it even further.
If you have any thoughts, concerns or insults. Please feel free to comment them below. Feedback is appreciated. I hope Hinterland or @Raphael van Lierop considers some of these. (at least the lighting ones).