You control the green planets. The number on the planet represent the planet population. Planet population increases over time. The maximum population depends on the size of the planet. Gray planet are uninhabitated. The number on such planets represent the number of ships needed to terraform the planet. Click on a planet of your own to select it and click on a planet to send ships to it. You gain a minimal amount of resources per day for every planet you own. Also, you must defend the planets.