Kerbal Space Program is the single best thing there is for teaching someone to understand the concepts of orbital mechanics. There are some steep learning curve

Kerbal Space Program is the single best thing there is for teaching someone to understand the concepts of orbital mechanics. There are some steep learning curves. However, once you figure out how to do something it becomes a piece of cake. I don't know of any other games/simulators that do such a good job of conveying understanding.