A tidally locked planet is one that's held in a state of suspension in which one face perpetually faces the sun and the other is eternally dark and also almost subzero cold
A wiki link to explain things better than i could scientifically
Basically, slightly pushing the defined lavaland lore aside for a second, this would throw out the mysterous and uninteractable necropolis gate for instead a large cave opening. Passing through would transport you to the planets other side, a whole new world at the furthest edge of the map where danger and minerals may be richest a frozen wonderland where the sun never shines.
Snowdin land (WIP name) is cold, veeery cold but survivable with a winter coat by normal human conditions with a similar pressure threshold, being faced away from the sun it is eternally dark with no respite, and vicious battering snow storms that can knock you around or even unconscious without precautions or coffee stimulants
The rocks hued blue quite generically are much the same, and winding caves are infested with the usual blend of monsters suited to the cold climate but have one pivotal difference in that they are totally or near immune to physical damage. The thick slippy ice is a new hazard, as running upon it can seriously hurt yourself from slipping, and walking over it may slow your pursuit of animals or create tension in being chased by a foe.
> Yetis - The apex predator of the ice wastes, these hulking humanoid beasts with luxurious fur, sought after for strength and resistance to cold, pressure and damage are a difficult foe, for they are immune to KA blasts. If you must take on one of these creatures without a plasma cutter or a laser, then you may have to resort to using a edged weapon to pierce the thick hide. They are uncommon and do not spawn from tendrils. They have a tendency apply a short knockdown stun and fling the player away from them when they attack (akin to a mech stun-punch but with greater range)
> Forgotten hivelords - The asteroid hivelords after the fall of the great asteroid upon the planet, took well to the climate but have crystalised due to long term exposure, their remnants have a low chance of embedding upon your person but melt away instead of falling out, it all depends on how well/lightly armoured you are in the chances of getting skewered. One of the few monsters who will receive damage in usual amounts.
> Blizzard Sows and Bulls - Relatively docile creatures that wander around but have a pete-like streak of momentary aggressiveness and the size and strength to burst through a metal wall when angered , butchering them gives good meat returns for hungry miner and the meat is in high demand, whilst applying a electric razor will shave off excess fur for yarn cloth crafting recipies. Herding them securely may be advised if you have a secure place to store them.
> Any combination of discarded away mission ice variant monster as seems relevant since they are largely unused all but for xenobiology research.
(Willing to take further suggestions, typically away from bizzaro lavaland monsters please)
Some things would also be different too due to the climate. Such as being able to collect piles of snow and craft them into bricks for igloos/snowball construction (so mining lavaland would be recommended by one team of miners and the mining slot could be expanded, so there is equal coverage given that iceland doesn't have sand.)
As soon as i can think of more to add i will edit this thread, but for the meantime feedback would be appreciated.
Stay cool.
