If you want to play Kerbal Space Program safely and support the developers, you should use official storefronts: Often features deep discounts during seasonal sales.
These sites often redirect you through multiple ad-heavy pages designed to trick you into downloading browser extensions or unwanted software. Kerbal Space Program Free Download (v1.12.3.031...
You will not receive official updates, bug fixes (which are frequent in KSP), or access to the Steam Workshop for mods. Legitimate Ways to Play If you want to play Kerbal Space Program