You found an oil field. And you have only a little money in your hand. Starting from buying the first device, using this humble device to continuously dig oil. Sell them to get income. Use income upgrade equipment to speed up the collection efficiency. When you accumulate a certain amount of money, you can buy new equipment to improve the collection efficiency. You can also hire managers to help you provide the operation of the entire company. Continuously develop and strengthen your oil company until it becomes the largest one in the world.