Gunman Chronicles
Gunman Chronicles was Rewolf Software's first and only game and was released in 2000. It begun as a mod, initially for Doom, then on the Build engine, then for Quake (https://www.pcgamer.com/games/fps/what-happened-to-the-creator-of-gunman-chronicles-valves-forgotten-fps-my-relationship-with-gabe-didnt-really-go-that-great/), then for Quake II (https://www.streamline-studios.com/post/streamline-spotlight-renier-banninga-creative-director) (for which a build exists) before becoming a Half-Life mod.
Although the team was spread across the globe, the last few months of development were done at Valve Software's office with Valve Software providing some staff to assist with completion of the game (https://www.pcgamer.com/games/fps/what-happened-to-the-creator-of-gunman-chronicles-valves-forgotten-fps-my-relationship-with-gabe-didnt-really-go-that-great/).
Following the game's release, the team disbanded, with many going on to work in the games industry. Renier Banninga went on to Streamline Studios and Chris Macarthur went on to Gearbox Software among others.
Gunman Chronicles shipped as a stand-alone game though appears to have made almost no changes to the Goldsource engine, outside of making the engine play a Bink .exe
video on game load rather than a .avi
file.
Valve Software retained right of first refusal for a sequel to Gunman Chronicles (https://www.pcgamer.com/games/fps/what-happened-to-the-creator-of-gunman-chronicles-valves-forgotten-fps-my-relationship-with-gabe-didnt-really-go-that-great/)