According to Cheat Code Central, Infinity Ward creates fine-tuned, but mostly conventional entries, in the "Call of Duty" series, while Treyarch attempts to add more innovative elements to the franchise. The two developers switch off releasing a new "Call of Duty" title each year.
Infinity Ward originally possessed sole developmental control over the popular shooter franchise, with their game "Call of Duty 4: Modern Warfare" being heralded as a major achievement and a huge step forward for the series. The game's single-player campaign offered a new level of cinematic grandeur, and the multiplayer cemented the game's classic status.
However, Infinity Ward played it safe with "Call of Duty: Modern Warfare 2," its next iteration of the game, offering only slight enhancements to the multiplayer and a single-player experience that most critics found disappointing. Treyarch's developer's releases were marked by attempts to differentiate their games from Infinity Ward's.
"Call of Duty: World at War," the company's first release, featured a new multiplayer "zombie mode" that proved popular with fans, but it was "Call of Duty: Black Ops" that truly separated Treyarch from Infinity Ward. The game's unique Cold War setting, flashback-framed narrative, and engrossing multiplayer made it one of the most popular entries in the franchise.