Wolfenstein (2009) belongs on GOG
Wolfenstein (2009) has not been sold digitally since it was removed from Steam on May 5, 2014. If you want a legal copy today, you are looking at a used PC, Xbox 360, or PlayStation 3 disc.
Raven Software developed it. Activision published it. It runs on id Tech 4 and continues from Return to Castle Wolfenstein: B.J. Blazkowicz, the town of Isenstadt, and the Veil. It was not a huge commercial success, and reviews were mixed. MachineGames later started a new chapter with The New Order. None of that is a good reason for the 2009 game to disappear from storefronts.
Return to Castle Wolfenstein and Wolfenstein 3D are already on GOG. This entry is the missing official follow-up in that library, and it is on the GOG Dreamlist for a reason. A DRM-free PC release would let people own the campaign without hunting secondhand discs.
The old complication was split rights between Activision and id/ZeniMax. Microsoft now owns both sides of that split. A careful listing — clearly titled Wolfenstein (2009), sold as the original game rather than a replacement for the later series — would close a real gap.
Please put it on GOG, next to the games it was built to follow.