^ "Look(s) easy." Real world rocket science is easier said than done. The game is designed to teach people how basic rocket science works, to teach people how the space program is run, and to let people have fun! Back to topic: If this game is to have an ESRB rating, E (Everyone) sounds reasonable. I can't decide whether the 10+ (10-years-old or older) tag should be included, though. If ESRB is to rate, though, it would be RP (Rating Pending). But all the ratings proposed are matter of opinions (even mine). I Googled "Kerbal Space Program ESRB" and this thread came out of it; no actual ESRB rating for this game. Maybe I should do a search on the ESRB website. And the truth is, KSP is rarely advertised (at least that's what I've seen).