What video game franchise does Rooster Teeth use for their show "Red vs. Blue"?

Rooster Teeth Productions’ Red vs. Blue: The Blood Gulch Chronicles is an ongoing series. It’s a spoof of FPS games, military life, and science fiction movies. The project, which was supposed to be a six-to-eight-episode miniseries, grew in popularity rapidly and unexpectedly. Season 18 of the series, Red vs. Blue: Zero, will premiere in November 2020, after eighteen seasons and five miniseries. It is the second-longest running web series of all time and the longest-running episodic web series of all time. The series has received praise for its uniqueness and creativity.