Update - 11/01/2024, 11:55 AM UTC: The GitHub repository has been restored now. Hopefully this won't happen in future, considering as noted below, GSC Game World actually gave it their blessing to be used. And thanks to the take-down, even more people now know about it. From the reversal notice, GitHub stated clearly after a review it was a fraudulent take-down.
Original article below:
OpenXRay is an improved cross-platform version of the X-Ray Engine, which is the original game engine used in the S.T.A.L.K.E.R. game series by GSC Game World. However, it seems a bad actor got it taken down from GitHub.
However, on X (formerly Twitter), the official GSC Game World account noted it wasn't their doing, and that "Open X-Ray is totally allowed to be used as a modbase" and that they're dealing with "a wave of false claims caused by our position recently":
So with that in mind, hopefully GitHub will reinstate it and prevent this from happening again from the same people trying to cause issues for them. It's also nice to see, at least according to who is posting on their social account, that they have no problems with people using OpenXRay considering it's based on leaked code.
The code has been out so long now, and used by so many for such old games, it would have been pretty strange to only now go after it. Especially since it requires data files from the original games to run, so people still need to buy the games to use OpenXRay.