Gearbox Software
From Halopedia, the Halo wiki
Gearbox Software is a video game developer founded by Randy Pitchford, Stephen Bahl, Landon Montgomery, Brian Martel, and Rob Heironimus in January of 1999. They are best known for a number of high-profile PC and console games such as the Borderlands series, the Brother in Arms series, the Half-Life expansions Opposing Force and Blue Shift, and the controversial Aliens: Colonial Marines.
Gearbox was also responsible for the PC port of Halo: Combat Evolved. They are also responsible for the making of Halo: Custom Edition. They have worked on the Brothers in Arms series and are currently developing Aliens: Colonial Marines. The Map Editing Kit was created by Gearbox and passed down to other selected websites.
Gearbox Software is located in Plano, near Dallas, Texas.