Pi Studios
From Halopedia, the Halo wiki
Pi Studios is a computer game software developer based in Houston, Texas. The company was founded in 2002 by: Robert Erwin - Business Development, John Faulkenbury - Production, Rob Heironimus - Design, Dan Kramer - Programming, Peter Mack - Programming.
They moved from their original location in Plano, Texas to Houston, Texas in January 2005.
Their first commercial work can be found in Activision's Call of Duty: United Offensive. They have also contributed to Call of Duty 2 for the PC and the Xbox 360.
They worked on porting the Halo games onto Windows Vista, the next version of Windows after Windows XP