Hello, I'm very happy to hear your comment :D
In this project I wanted to introduce a lot of different mechanics, but they couldn't be implemented, because of the time. I plan to put the gold in the future and even add another type of coin.
The game is very inspired by the game "Caves" that is for android, but it has and will have several differences.
Answering your questions:
What is the meaning of pickaxe?
It's being able to enter parts that you can't enter. And I also wanted to implement minerals, but I haven't been able to do that.
Also to say that everything is very expensive, because the game lacks to be balanced. xD
Also the game of the moment does not have end, it is only to advance and to advance. In the version of github I have implemented (a little) the theme of achievements.
At this time I should not update the entry to include features as it would be like cheating, then I will update it after the jam finishes.
I will also continue working on the game, I will release a version for pc and also for android :)
Thank you