A fun challenging game!

[Muffins]

https://kerbalspaceprogram.com/download.php

I do recommend downloading this game its really fun when you finally get your space shuttle and learn how to do it! There is a demo you can download at the bottom of the screen if you want to try it and if you really like it you can buy it on steam and it is updated regularly.

[Leetgrain]

Already had a thread for this yonder ago, by Monp, I miss that guy q.q

But yeah, that game was hecka fun, haven't tried it since it's become retail

[Christovski]

What is a Kerbal

[Mr_Rainbow]

http://www.youtube.com/user/kurtjmac

This guy has been playing KSP for awhile so if you want to learn anything watch some of his!