There are plenty of fun sci-fi and space-themed games out there. But precious few are grounded in realistic physics. Kerbal Space Program is as much a full on NASA-simulator as a game. It nicely uses the scientific method to keep you tweaking your journey toward galactic discovery.
Kerbal Space Program is a deceptively dense game hiding behind the cute green Kerbals that populate this space-age world. In Career mode you’re given a basic NASA-like facility. Buildings include Vehicle Assembly, Tracking Station, Mission Control, and a launch site that’s little more than a slab of concrete.