The game that started it all. Call of Duty did away with the FPS genre's "lone wolf" mentality, putting players in the shoes of various Allied soldiers in WWII struggling to defeat the Third Reich.
Finest Hour was Call of Duty's console debut, hitting PS2, Gamecube and Xbox. In the beginning, the PC and console games were separate.
Once again set in WWII, Call of Duty 2's sprawling single-player contained three separate campaigns across 27 levels. It's especially notable for being an Xbox 360 launch title.
Big Red One got its "unique" name from the real-life Army Infantry Division that the campaign follows. The game is notable for employing the voice talents of numerous Band of Brothers actors.
Call of Duty 3's 14-mission campaign is unique in that it follows a single historical event - the Normandy breakout. It also represents a complete shift to consoles - it wasn't even released on PC.
Call of Duty 4 brought the franchise into the modern day with a contemporary storyline and setting. Although the single player was short and sweet, this is when the franchise became the multiplayer juggernaut it remains to this day.
Taking a franchise known for sprawling campaigns and elaborate multiplayer and shrinking it down onto the PSP's smaller screen is nothing if not ambitious, even if it didn't quite reach the bar set by its predecessors.
Treyarch's World at War brought Call of Duty back to its WWII roots. Gamers also have World at War to thank for the introduction of Call of Duty's ever-popular Zombies Mode.
Final Fronts is one of the lesser-known Call of Duty entries. The game was released for the PS2 in 2008, after the franchise made the jump to next-gen with Modern Warfare and World at War.
Modern Warfare 2 further refined the frantic, fast-paced multiplayer formula that made Call of Duty 4 such a breakout success. It once again made Call of Duty multiplayer one of the most dominant multiplayer experiences on any platform.
There's been a lot of Call of Duty games on the Nintendo DS - five of them, to be exact. They exist in a sort-of alternate Call of Duty universe, starting with Modern Warfare in 2007 and concluding with Modern Warfare 3: Defiance in 2011. Mobilized might be the best of the bunch. It is technically accomplished, has a lengthy campaign plus multiplayer, and its own version of mouse & keyboard controls courtesy of the DS's touch screen.
The iOS App Store has received a couple of stand-alone versions of Call of Duty's beloved zombie mode, beginning with Call of Duty: World at War - Zombies in 2009 and continuing with Black Ops Zombies.
Call of Duty: Black Ops took the franchise's storytelling to new heights with a twist-filled narrative told by an unreliable (at best) narrator. Developed by Treyarch, the multiplayer brought back a greatly expanded Zombies Mode, and improved traditional multiplayer with a new currency system.
Modern Warfare 3 overhauled the entire Killstreak system in multiplayer as well as adding a new cooperative mode, Survival.
Call of Duty: Black Ops II most notably introduced two completely different eras in one campaign, meaning players jumped between 1986 and 2025.
Declassified had an opportunity to be a great portable shooter, but ended up falling flat. It was still cool to see true twin-stick controls in a handheld Call of Duty, though.
Strike Team on iOS spices up the Call of Duty formula by letting players seamlessly switch between an overhead tactical view and traditional FPS action, but the results were mixed.
And with Call of Duty: Ghosts once again kicking off a new generation of gaming with some of the most realistic graphics we've seen to date, we can't wait to see where the Call of Duty franchise goes next.