Crates spawn randomly. If you don't see one, click the sell button. Choose any crate and click on it. A material will appear. More clicks on a crate result in a higher valued material. Once you are satisfied with your materials, you can sell them. When you reach enough cash in the game, you can proceed to the next tier. A button will show up. There is also the option to mute the music, sounds, or both. Click the button on the left of the sell button to do so.
Like Miner Heroes, Candy Collector, and Wondered Discoverer? Here is Wonders of Discovery, the new game that combines features from all three. All songs are not originally mine; I only made remixes. The game does not save currently.