Some of the mechanics are kind of vague. It took a while before I figured out that the cursor collects loose ore. And I didn't even know that you can scroll down, I was waiting for the screen to auto transition.
I recommend a tooltip or some kind of explanation for what the cursor does. And have it so that your can scroll down slowly between levels rather than hard flipping between them. And make each level just a tad bigger than your screen so you have to scroll to see the bottom in the first place. This would teach players that you can scroll from the get go, and maybe have an arrow appear pointing down to the next level once the drones break through.