Kerbal Space Program is a computer game in which the player can build spacecraft, aircraft, and spaceplanes to their own design and use them on missions, both robotic and with crews, to explore the planetary system of the star Kerbol. The space program is conducted on behalf of the Kerbals, inhabitants of planet Kerbin, and the player manages the space program, advancing in technological capability, ambitiousness of missions, and size and skill of the kerbonaut corps. //

One thing which is certain is that after you've spent some time with Kerbal Space Program you will develop an intuition about orbital mechanics which few people, even authors of “hard” science fiction, have.