Fairly good, but could use some polish.
A very well-thought out game, I like the monstrous looks. I do think, however, a little bit more variety and some new creatures would be very good, as well as a risk assessment to determine if you want to put your miners in specific locations. I also think that the crafting system is very, very hardcore, and should either give a higher chance for success, or possibly a chance to keep the items, but still fail the recipe. And lastly for critique, I think that perhaps a more accurate wild monster rating is in order. For instance, class 5 monsters are approximately level 100. If you knew wild monster's levels, it'd be far easier to explore without killing your monster. Other than those points, the game is very well done. A few more monster types, some more interesting places to go, perhaps even limited multiplayer capacity, seeing as the fight system is automatic. I like the game, and congratulate you on a good piece of work.