70		E.S.S. (DOS, 1989)
43		RAM Ghost (Windows, 2013)
41		Zombie Smashers X3: Ninjastarmageddon! (Windows, 2007)
40		Moon Tycoon (Windows, 2001)
40		Star Merchant (Windows, 2017)
40		Air Traffic Controller (DOS, 1985)
40		ATCsimulator2 (Windows, 2004)
40		X: Beyond the Frontier (Windows, 2000)
40		Oolite (Windows, 2006)

Notes: Games similar to Kerbal Space Program, Games like Kerbal Space Program, Squad, Squad, Windows, Simulation, Sci-Fi, Futuristic, Managerial, Business Simulation, Real-Time, 3rd-person, Other, Flight, Aviation, Unity, PC, Game Similarities.