What is Harder Solar System? Harder Solar System is a step up in difficulty from the stock system. The main difference between this solar system and stock is that the entire solar system has been rotated to simulate an axial tilt for Kerbin, the same concept that gives Earth an axial tilt in Real Solar System. Also, the Kerbal Space Center has been relocated to a higher latitude. The combination of these two changes forces players to plan launch windows for things that did not typically require