Arx Fatalis is a partially open source first-person role-playing video game for the Xbox and Microsoft Windows, released on November 2002 by Arkane Studios, a video game developer based in Lyon, France.
The design of Arx Fatalis was heavily influenced by games from the now-defunct Looking Glass Studios, especially Ultima Underworld. Arkane Studios have stated that Arx Fatalis was intended to be Ultima Underworld III, however they could not obtain a license for the UW name.
Read more about Arx Fatalis: Premise, Gameplay, Controls, Source Code Release