FreeWolf was a project to create an equivalent for Wolfenstein 3D in the style of Freedoom, the free software total conversion for Doom. An idea that has been mooted multiple times, the most serious attempt occurred in 2017 which produced several textures and some sprite drafts by Doomjedi, Military, Lozer 42 and Sigma64. That same year Military also worked on a Wolfenstein mod using graphics from the actual Freedoom. Another prior attempt was made in the orbit of Freedoom itself in late 2015 and early 2016.
Other proposed titles for such a game have been Librestein. Freiheit (German for "freedom), Dogstone, and Operation: Direwolf.
A free replacement project for Rise of the Triad was also alluded to in this 2015 forum thread.