For a game like this, that’s pretty hard to think about. Still, something like the expeditions into the caves or a forest (I’m talking about the snow map mainly for most if not all of these) that have harder enemies but yield better rewards like different metals or somehow, plastic that could get you out faster.
Maybe the players can also have a stat mechanic where doing different tasks can increase their knowledge of a stat that gives benefits. This could reinforce the teamwork part of the game.
Strength : Makes mining and chopping down trees faster, slightly increases melee weapon damage. Higher levels allow you to use heavier weapons. (this should strictly apply to melee, not any ranged weapons.)
Knowledge : Allows you to use resources more effectively, slightly reducing the amount needed to craft, and expands your crafting knowledge, allowing you to craft new objects with different resources depending on your level.
Adaptability : Makes your body adapt faster to your environment, causing your temperature to lower/rise less rapidly, also makes you more resilient to disease or infections from animals. Higher levels allow you to adapt to weather conditions faster.
Craftsmanship : Allows you to make higher quality tools and disassemble plane parts (and maybe other things in the future) in a shorter time (and possibly gain more resources like more metal scraps or bolts if that’s ever a thing), greatly reduces the amount needed to craft depending on the level.
Cooking : Allows you to make higher quality meals that yield more points of hunger and increase the speed at which you cook.
Observation : I noticed random footprints in the snow scattered around the map. Instead of everyone being able to see them, those with certain levels of observation will be able to see them (piles of snow that may hold rare objects that can be dug up using shovels or something). Maybe footprints can lead to igloos, lakes, outposts, caves, and other things but the footprints that lead to each can only be visible depending on your observation level. Higher levels will lead you to things like outposts where you will have to fight actual guards and stuff who are much harder than polar bears, but you can get much better rewards and resources, maybe even armor.
Builder : The builder can build things faster (building should take time to do, just like preparing meals (which should also take skill but can also be considered mastered at max level)). They could repair structures after they are damaged (damage can be caused by avalanches and boulders or something).
also maybe you can get guns from the outpost and not make it with 10 wood, 10 wood.
Also since I think I forgot to talk about the description:
Make the game more challenging so that meat can only be cooked using a campfire and that killing animals doesn’t drop any wood. (You can only get it from an axe and chopping down trees, but there will also be polar bears in the area reinforcing the survival aspect of the game.)
The weather is not at all unforgiving. I saw an avalanche but all it did was make smoke surround the map for a day or so, and then it was over. Nothing rolled down the mountain and further destroyed the plane or anything that I or anyone else built, it was just as simple as that. Make avalanches a challenge.
Polar bears are a constant threat if you’re a child who doesn’t know how to craft or don’t have a gun. One bullet and they’re dead, and around 3-5 bullets if they are the black polar bear. Give them more health, and also make it so that some of them have a chance to have a virus so when they bite a person they may get it.
Imagine getting bit by a polar bear (or one of their cubs if you want to make that a thing), then you get Avian Influenza, Canine Distemper Virus, and Morbilliviruses. That would make things much more challenging, especially if you or anyone else didn’t know how to treat it. (not sure if polar bears can get rabies, although if they can I would research it.)
These diseases and viruses could give players a variety of effects, visual, physical, and maybe even mental, and some could also lead to death.
This could mean that you could also add a stat build (medic) that knows how to treat viruses and diseases, this would also have to result in players resting so that they could heal from their medical problems.
This could also lead to bandages being a thing, which you could probably find at outposts and maybe rarely in igloos.