Been playing the game for a few days now and I've really enjoyed what is here, never had a game with such in depth and detailed mechanics to keep yourself alive. While I personally enjoy it, despite not being that much of a very brutal and hardcore survival kind of player, I do have a few hang ups on the game so far I'd like to point out as personal opinions.
Firstly, the Death Spiral. Of the many runs I have, even with turned up loot the game often usually ended in a brutal death spiral where one problem turns into many, and while I do for the most part consider it entirely my fault in some, others it felt more or less just a bit frustrating at times. I actually really like that so many factors play into one another for how your character preforms actions but as it stands at the moment I think its a little too easy for you to spiral yourself at times.
One of the causes, and another smaller concern for myself on the side, is the pace of the game where it feels like a confliction in design. One where you have to head down quickly to reach your goal or find new supplies since digging through walls exerts you so much and takes a lot of time, while on the flip side you also want to take your time to not miss valuable resources that could save your life if you hit a trap or have a bad fall later. A lot of the injuries in the game take time to heal and while sleeping them off could help it comes at a huge cost to your over all health because sleeping leads you to starving or being dehydrated, two massive issues on their own as a trade off for somewhat fixing long term issues or other problems. Personally I think sleeping, thirst and hunger should all be slowed a lot down to help prevent spiraling into death because of them and trying to rest off other wounds. It would also be nice if sleeping helped cure ailments or fixing wounds faster as long as the quality of the place you sleep is decent enough.
Speaking of sleep on its own, more often than not, due to how often you have to sleep in this game it makes it rather hard at first to judge when exactly you should go to sleep. You can't sleep manually if your not tired enough, which I would change personally if you have a wound or sickness you are trying to aid. Encouraging you to rest when you are hurt to fix yourself allowing the player to take things a bit slower since one wrong step is all it takes to end your life in this game already. As it stands now, you can only really rest if your satiated and saturated. Full and not thirsty. If you sleep when either of those are low it can lead to starvation and dehydration fast and those end up getting you killed since both effect your performance in doing anything. I would also chance it so that if you pass out from the lack of sleep forcefully, even if it would kill you, you stay asleep until 25% of your sleep need is returned so you don't get stuck in an endless loop like I have multiple times where just barely enough liquid is sloshing around near by you it wakes you up by force and then knocks you out again since you are at 1% sleep. Another spiral of death that you just have to sit and accept since you can't mine, jump, or move away if you are in just a deep enough pit.
I'd also personally like even more hazards to be wary of. (This is coming from a player who struggles to get beyond the third layer. Might be more hazards I'm unaware of but its hard enough for me to get to them that I never actually encounter them, just keep that in mind.) Spiders and the swarm are both awful problems to deal with as is, along with traps but events like the Earth Quake don't really feel all that threatening unless you are injured and loosing control with a head injury. I'd personally like to see the Earth Quake be more dangerous, maybe not throwing you around but causing mini cave ins around you, falling blocks that can hurt you, passages shifting or something along the lines that makes traversal more difficult. I'd lean away from just tossing the character around at random as it just feels awkward when you are entirely healthy. Maybe slow movement speed instead to simulate them balancing themselves out and holding themselves steady to not be thrown around while rocks fall around them and they try to avoid getting knocked out by a stone hitting them directly in the head. Or the ground breaking under them sending the character to the abyss with poor positioning or just bad luck.
TL/DR: I would lean more into the slow pace of steadily making your way down in the game. Leaning more into taking your time and fixing yourself up over time as you make your way down. Slowing down your needs a lot, allowing for manual sleeping when your hurt or feel like you need it, or at very least resting, (Like holding still long enough you sit down or lay down to recover faster) But I'd still like the game to be brutal as is. Right now it feels a bit too unforgiving for taking slightly too long or going slightly too fast. Getting caught in Death loops is very very easy due to your total over all health affecting everything from movement to mining to even visuals. Trying to take your time currently leads to death more so than trying to push through which is usually 50/50 on finding something good or falling and breaking several bones, dislocating your ankles, causing internal bleeding and reversing your controls with head injuries. I love the game so far but considering how long it takes to actually heal yourself from problems, I'd slow the pace of the game down a little, like the needs for food, water, and sleep to compensate to allow you to focus on finding things you need to treat the most common injuries and diseases. I feel this would make for an awesome 2D immersive sim where slow and steady, along with careful preparation goes a long way to your success, while making it all that much more painful to die when everything was going right until that one big mistake you made.
In the end I wish nothing but the best for the Dev and I hope they keep creating because I'll be keenly watching and ready to give feedback and support to what could potentially end up being one of my favorite games to play in the future!