Reposted link and dev posting from r/4XGAMING
https://www.reddit.com/r/4Xgaming/comments/91bacj/star_ruler_2_is_now_fully_open_source]

"GGLucas

Hi everyone. One or two of you might remember me as one of the original developers on Star Ruler 2. Blind Mind Studios has been inactive for a few years and we weren't doing anything with SR2 anymore. We figured it would be nice to release the source code, in case anyone wanted to see how the engine works.

The repository includes basically everything needed to build and run the game, I tried to clean it up to make it as straightforward as possible."

So this is the reason why it was never on sale in this year .

These are always good news. Thanks for the info!

https://github.com/BlindMindStudios/StarRuler2-Source/tree/master/data

>The music is not part of the open source release of Star Ruler 2
https://github.com/BlindMindStudios/StarRuler2-Source#differences-with-commercial-version

Well, its not that much of requirment actually.

Anything about DLC's sources, btw? Didnt check much of repo yet

You will have to compile it yourself, with Visual Studio 2017. And it doesn't include the music assets from the game. But they can be copied over from the commercial game and will be used normally then. Here are the differences from the commercial build.

"The music is not part of the open source release of Star Ruler 2. The data/music/ directory from the commercial release can be copied directly into the data/ directory of an open-source build. The music will be detected and played.
All code for accessing the SteamWorks API has been removed. The game platform abstraction layer game_platform.h has been kept intact, so other mod-sharing platforms could potentially be integrated into the game.
Code for the automatic game patcher that is part of the GOG.com release is part of the repository, but the functionality is disabled, since it relies on delta updates and will not work with modified open source versions.
While the actual source code is probably still compatible with 32-bit platforms, project files and external dependencies for 32-bit builds are not included in this repository."

I guess compiling it with Code::Blocks will require some extra work. Somehow I never trusted Visual Studio...

Well, it is after all Microsoft Vusal Studio.

It's a solid 4X with some interesting ideas (the diplomacy "card" system in particular was kind of neat). Sad to see that they didn't do well with it, but I guess it came out in a bit of a space 4X glut.