This was really fun! I liked digging into the ground to find ores, make money, and level up my skills so I could dig deeper. It's a really solid gameplay loop, and it was fun trying to see how far down I could go. It's also cool that each level/day is randomly generated, I liked exploring new random caverns as I went deeper. I guess a tiny nitpick is that it takes a few seconds to load the next level each time; maybe one idea could be to generate bits and pieces of the next level as you explore the current one, like you generate a couple of blocks per frame, so that way when your oxygen runs out the next level is already generated.
Overall, very well done with this game, I enjoyed it a lot!