I had a lot of fun playing this for quite a while. Getting more ores and gems then returning to sell is a great loop, evocative of Miner: Dig Deep. I do wish that there was more of a sense of progression, once I spent long enough getting down to places that required an upgraded pickaxe, the rewards did not seem to be significantly more than I was making in the higher up areas.
Overall very enjoyable and addictive.