This is a 4x game (Explore, Expand, Exploit, Exterminate) . “Select from one of seven races – or craft your own – to explore dozens, hundreds, or even thousands of systems in a galaxy of your choosing. Expand across unique and varied planets and ultimately exterminate – or subjugate – any who stand in your way either in offline single player or up to 28 player multiplayer.” as gog.com put it.
But as well as being available on Gog.com or Steam, it’s also open source but that doesn’t include the music from the game. So you can pay for the game on Gog.com/Steam or download the open source version and build it yourself.
The GitHub website contains the full source code needed to build Star Ruler 2, and all secondary scripts, data files and assets required to run it. It’s 45% C and 22.5% C++ according to GitHub with a sprinkling of Flash (arr ar- saviour of the Universe- er sorry).