Gunman Chronicles or Half-Life: Gunman (previously Gunman: TC and simply Gunman) is a futuristic first-person shooter

First-person shooter

First-person shooter is a video game genre that centers the gameplay on gun and projectile weapon-based combat through first-person perspective; i.e., the player experiences the action through the eyes of a protagonist. Generally speaking, the first-person shooter shares common traits with other...

 video game originally created as a mod by the now defunct Rewolf Software

Rewolf Software

Rewolf Software, also known as Rewolf Entertainment, was a game development studio established in Utah by Herbert Flower in 1996...

. Gunman Chronicles was originally a Quake deathmatch mod named Gunmanship 101, then it was moved to Quake II

Quake II

Quake II, released on December 9, 1997, is a first-person shooter computer game developed by Id Software and distributed by Activision. It is not a sequel to Quake; it merely uses the name of the former game due to Id's difficulties in coming up with alternative names.The soundtrack for Quake II...

's engine before becoming a Half-Life mod. At the Half-Life Mod Expo in 1999, Gunman Chronicles stole the show and Sierra approached Rewolf to make a retail version.
After significant work, Rewolf was given some office space, funding and a mapper (Jeff Lane) by Valve Software to help complete the project.