1. Summary
2. Background
3. Hype

Those that were introduced to the Call of Duty series with Modern Warfare were treated to a gorgeous game that blew away many expectations. What they may have not realized, however, is that Call of Duty has its roots much deeper than that. In fact, it has ties to what is arguably the creator of the World War 2 FPS and its own direct competitor. That's right, Call of Duty is derived, somewhat, from Medal of Honor, and its convoluted history shows how much it has evolved past its inspiration and competition.

Call of Duty was originally for the PC and PC only. Created by Infinity Ward, which had recently split from 2015, Inc. (creators of Medal of Honor: Allied Assault), it also took a cinematic approach that emphasized the mayhem of warfare. It won over critics, and publisher Activision decided to turn it into a franchise to compete with EA's Medal of Honor. In a way, Call of Duty is one of the big guns in the publishing war between Activision and EA, and further releases have only solidified this sentiment. Call of Duty received an expansion pack titled United Offensive, which introduced things to the series that would show up in later games, such as multiplayer ranks that offer perks (although it was not persistent in United Offensive). It is also remarkable as being the first Call of Duty-related game created by Treyarch, which went on to develop almost half the games.

Next came Call of Duty 2, once again developed by Infinity Ward. Sporting an incredibly modified Quake 3 engine, it was absolutely stunning and went on to garner critical acclaim and a solid commercial presence. It upped the ante in just about every way, from graphics to presentation. Much like Halo on the original Xbox, Call of Duty 2 was the killer application for the Xbox 360 at launch, and it still sees play in single-player and multiplayer on both systems to this day. It did not receive an expansion pack, and Treyarch used the Call of Duty 3 moniker for a console-only sequel that PC users never got to play.

The next Infinity Ward Call of Duty decided to break the mold of World War 2 shooters and enter to the equally burgeoning genre of modern-era shooters. Titled Call of Duty 4: Modern Warfare, it quickly became one of the most played multiplayer games online, and still holds that position to this day, almost two years later. It managed to keep the style of the previous two titles while shifting it to a modern setting, and it introduced persistent stats that hooked gamers to the multiplayer. There's nothing quite like gaining levels by shooting people in the face, and Call of Duty 4 has that. Call of Duty 4 also has a character from the second game, Captain Price, which established a definitive continuity. Finally, the nuclear explosion scene is still one of our favorites in gaming, and somehow manages to wrench your gut even if you know it is coming. Now that is masterful.

Treyarch decided to go outside their console safe-zone with Call of Duty: World at War (also known as Call of Duty 6). Placed once more in the World War 2 setting, it was a big improvement over previous Treyarch productions, and is best compared as the World War 2 version of Call of Duty 4. It may not have been perfect, but the multiplayer is great and the single-player retains that cinematic feel. It was certainly a very solid entry compared to Call of Duty 3 or Big Red One, and marks the first game that Treyarch made that was almost up to the standards that Infinity Ward adhered to.

Finally comes Modern Warfare 2,which is a continuation of the original Modern Warfare. Set to release within the next two months, there's been a ton of hype about it, thanks in part to the enduring popularity of Call of Duty 4. While there is no doubt that it will live up to a lot of this hype, it is hype nonetheless, and we all know what happens to hype. It gets demolished.