build a own solar system

First build your own sun, decide the mass, and size

Second build your planet in the system. You can choose the category, decide the mass ,size, distance from the sun, how many satellites it has, the gas composition, solid composition or liquid composition, rotation speed, and appearance. This parameters all affect the temperature, whether the planet is steady ,has livings or not. And all the planet obey the low of universal gravitation, you should take care of the distance form the sun or the planet will be destoryed.

Finally you can see one solar system created by you own. You can travel in and update it. There is gui to easily describe the situation of any object for better education.