The atmosphere is immaculate! I love the vibes of this demo, it's just so nice and the graphics just accentuate everything. It really all flows together nicely, and it feels like you tried to make all the elements just fit into the game idea, which is great design.
Playing it was also just very fun. The gameplay loop keeps you engaged, and provides things to strive for. Though it was a bit too easy at times, I didn't really feel at any point that I was in danger of losing, even if there were multiple enemies attacking my camp. Moving through the mines also didn't feel like a challenge, just destroying one rock and manoeuvring to the salt or other crystals was very easy. Exploring felt nice, I was hoping to find more actually, I was very happy when I found the cat :d A shame I didn't notice any way to use its assistance, but it may obviously be not implemented yet.
A weird thing in the mines was that there was a bunch of blue crystals, but I didn't see any way to use them? Perhaps just adding some blue crystal costs to available upgrades would be nice, as after noticing their lack, I didn't feel any need to loot them.
In terms of shooting part of the game, it's very nice and snappy. Some feedbacks are that birds are really annoying, but it may be intended :) Also the bees felt weird, because after shooting them down, I tried to aim for the beehive still, but it didn't register as a hit, even though when they got damaged the beehive also flashed red, so I assumed it's still a part of them.
I also found some small bug, because while moving forward against a rock column in the mines, the Solianiko would disappear behind it :d
Overall though, amazing job! It really feels like an actual demo for a fully polished title, and a title I'd very gladly play at that. The graphics and animations as well as audio just make for a very flavourful experience. I can't wait to play more of it, when you release more content. Great job and good luck!