Games that adapt main series titles, but feature different storylines, acting as side-stories to them: While only United Offensive and Warzone are listed as expansion packs, additional content was added in all other games through minor DLC packs. A sequel to Call of Duty: Black Ops, still set during the Cold War era.
A free DLC for the game was also released as a stand-alone title for free: A reboot of the Modern Warfare subseries.
Only its single player campaign was released for PlayStation 4, Xbox One, and PC in 2020 as Call of Duty: Modern Warfare 2 Campaign Remastered. Formerly simply known as Modern Warfare 2, it's a sequel to Call of Duty 4: Modern Warfare, set in 2016. Call of Duty: Modern Warfare 2 (November 10, 2009), PC, PlayStation 3, Xbox 360.This game also introduced the Zombies mode, which returns in most later games and features a separate storyline. Set in World War II, it starts the "Black Ops" storyline. Call of Duty: World at War (November 11, 2008), PC, PlayStation 3, Xbox 360, Wii.Taking place in modern day, specifically the year 2011. Also released in 2016 for PC, PlayStation 4 and Xbox One as Call of Duty: Modern Warfare Remastered.
Later also released for Mac and for Wii, this version titled Call of Duty: Modern Warfare: Reflex Edition and featuring some new mechanics.