On the topic of KSP: Some guy on /r/spacex modded KSP to hell for realism then recorded a video demonstration of how the boost-back will/could work: http://www.reddit.com/r/spacex/comments/1z6vyt/boostback_dem...

The first video explains the modifications to the game, mainly more realistic aerodynamics, realistic fuels and engine capabilities, a realistic planet and launch site. The second video is him actually performing the mission.

There are a few differences between what he did and what we now know is actually planned, but it's still pretty damn close and demonstrates the feasibility of the concept in a pretty intuitive fashion.