Nice demo, ended abruptly, it's a fun game. I've shared my feedback below and I hope you find it helpful.
Once I got a few dwarves, I found it frustrating how quick the dwarves would start mining before I had a chance to give paths and how short the torch is. Felt like I couldn't keep up with giving them paths to mine, most would end up randomly mining before I had the chance to lay enough paths and then the torch would burn out. Adding a way to pause and add routes, or a small delay at the beginning of each round to layout some routes for them to beforehand might help. **Replaying it with a different strategy of just selecting big blocks to make pathways to big collections of ore to mine, it felt more fun but I found I was waiting longer as they mined empty blocks, so it was less efficient, and I felt disincentivized from continuing this strategy with such short torch life.
Seemed like the only useful resource to mine was gold? Not sure if I missed it or if the other resources did anything, or if it was just limited to the demo, or if they were used by the base buildings? **Replaying it with a more keen eye, I found we're mining ore that gets sold for gold on the result screen. I'll keep the comment here in-case the feedback is helpful.
The base buildings were confusing, I made the mistake of unlocking multiple at once and I had no idea which icon represented what building. It's also not obvious what their inputs and outputs are when placing or after its been placed, so knowing where I should place them felt like guesswork. Would be nice to see some indication of that on each building, and be able to move them to different locations after they've been placed.
The distinction between expedition party and mining party wasn't clear to me at first. I didn't realize it was a separate group since I was just going mine -> upgrades -> mine. Might be more clear if we got to place 1-2 initial buildings before we saw any expedition party upgrades.
It's not clear when I want to mine for resources or mine for the exit, or what the advantage (if any) there is to reaching an exit, versus trying to mine everything. The first run I completely missed seeing how many mines I have left to run before it collapses.
I found myself accidentally dragging 1 square too far and then having an extra row/column that I wanted to delete. Fortunately it is easy to delete entire rows/columns, but I'd prefer having it work more like a temporary bounding box, where it only actually selects when you release the mouse button, akin to how RTS games work when you select troops.
The Brittle Master upgrade says 250 + 2 and is always greyed out, feels like I'm missing 2 something but I don't know what.
The colour difference between a mid-upgraded and fully upgraded upgraded is too similar to each other, as a light brown and yellow it's hard to tell at a glance what can be further upgraded.
Sometimes I noticed a dwarf will claim a tile to mine from across the map, and other dwarves will leave it to mine something else, and it's kind of annoying when the torch runs out before it gets there.