Help the beautiful miner to collect all gold she can. Explore the ground tunneling in any direction around you. Your goal is to reach at least the first golden milestone that you see in the milestones indicator. Both when you move and when you dig you lose strength (you see how much remains to you in the indicator at the top corner). When digging you will find golden nuggets, that go to your backpack; you can empty it going to the shop that is on the surface, where you can exchange the gold for money, and then you can use the money to buy supplies that help you to complete the excavation of the mine. For example you can buy explosives that open tunnels much faster, or brackets to use under the rocks to avoid their collapse.
Arrow keys to move, or move the mouse and click on the way you want to move; if you click far or you drag and drop to a far place you'll move more. To dig, click at an adjacent square. It's a complex game and you have to explore it to find how to advance applying the multiple items and bonus you find on the way, but essentially it's played with mouse clicks.