Call of Duty Series Guide — From WWII to Modern Warfare and Warzone
How the Call of Duty series began, the multiplayer rules Modern Warfare changed, how the series evolved, and which entries you can play in 2026.
Call of Duty is a first-person shooter (FPS) series that has released a new entry almost every year since 2003. It started as a PC game about World War II, but has since grown into a massive franchise spanning campaigns, multiplayer, Zombies mode, and battle royale.
In this post, we cover the background in which the series was created, why Modern Warfare is considered a turning point, and the structure of multiple developers taking turns, along with how the sub-series have evolved.
At the end, we list the games and platforms you can play as of October 2026. Sales figures and dates include only what we confirmed on Wikipedia and the official site.
At a Glance
| Item | Details |
|---|---|
| First release | October 29, 2003 (Windows) |
| Developers | Infinity Ward (later Treyarch, Sledgehammer Games, Raven Software, and others) |
| Publisher | Activision |
| Platforms | PC, PlayStation family, Xbox family, mobile, and more |
| Genre | First-person shooter (FPS) |
According to Wikipedia, the series had sold more than 500 million copies in total as of October 2023, with around 100 million monthly users across all platforms combined. It's also recognized by Guinness World Records as the best-selling FPS series.
Origins
Infinity Ward, which made the first game, was a new studio founded in 2002 with 21 people. Many of its members had been core developers of Medal of Honor: Allied Assault, a World War II FPS released the same year. Development, led by Vince Zampella, began in April 2002, and by May 2003 the team had grown to 27 people. Early in development, the project's nickname was reportedly "Medal of Honor killer."
The engine was a modified version of id Tech 3, used in Quake III Arena. The first Call of Duty, released for Windows on October 29, 2003, depicted the European front from the perspectives of three nations: the US, the UK, and the Soviet Union.
What was new about this game was its allied AI. Your fellow soldiers move according to the situation and help the player, giving a sense of fighting as a squad, unlike earlier FPS games where you single-handedly swept through enemy lines. At launch, it won Game of the Year awards from several outlets. However, many also consider it dated by today's standards, and it often places low in series rankings.
Gameplay
The series is generally built on three pillars.
- Campaign: A cinematic single-player story mode. Carrying out missions while switching between the perspectives of multiple soldiers has continued since the first game.
- Multiplayer: Competitive modes like team deathmatch, domination (capturing points), and bomb planting. You earn experience to rank up and unlock weapons and equipment.
- Zombies: A co-op mode first introduced in 2008's World at War, in which you hold off waves of zombies round after round. It later became the signature mode of Treyarch's games.
In terms of controls, the first game was one of the early FPS titles to adopt aiming down the gun's actual sights (iron sights). Starting with Call of Duty 4: Modern Warfare, the series used regenerating health, where you recover by taking cover and waiting after being hit.
In 2020, the free-to-download battle royale Call of Duty: Warzone was released. According to Wikipedia, it surpassed 50 million players in its first month.
Why It's a Classic
The series' turning point was 2007's Call of Duty 4: Modern Warfare. Infinity Ward had wanted to move beyond World War II after Call of Duty 2, and made this game with a modern warfare setting. It was the best-selling game worldwide in 2007 and had sold about 16 million copies by November 2013.
Its bigger impact was on multiplayer. Modern Warfare bundled the following elements together and made them something like the standard for FPS games that followed.
| Element | Details |
|---|---|
| Experience and ranks | You earn experience for actions like kills and capturing points, and your rank goes up |
| Create-a-Class | Build your own loadout from a primary weapon, secondary weapon, attachments, special grenades, and three perks |
| Perks | Special abilities such as extra explosives or increased health |
| Killstreaks | 3 kills without dying gives a UAV recon, 5 kills an airstrike, 7 kills an attack helicopter |
| Prestige | On reaching the max rank, you reset your rank and receive a new emblem (console versions, up to 10 times) |
The development team initially tested a system where you had to capture specific areas to receive air support, but switched to killstreaks because it disrupted the flow of deathmatch. They also had players choose their gear before the match to cut down on time spent searching for weapons. Thanks to these design choices, a structure emerged that let newcomers jump in easily while continually rewarding skilled players.
In short, Call of Duty is considered a classic because of its fast-paced gunfights, a reward structure that gives a sense of progression even within short matches, and a production system that has steadily refined all this year after year.
The Series and Its Influence
Call of Duty is developed by multiple studios taking turns. The main sub-series are as follows:
- World War II: Call of Duty (2003), 2 (2005), 3 (2006), World at War (2008), WWII (2017), Vanguard (2021)
- Modern Warfare: Modern Warfare (2007), 2 (2009), 3 (2011), and the reboots Modern Warfare (2019), II (2022), III (2023)
- Black Ops: From Black Ops (2010) through II, III, 4, Cold War, 6, and 7 (2025)
- Other entries: Ghosts (2013), Advanced Warfare (2014), Infinite Warfare (2016), and more
On mobile, Call of Duty: Mobile, made by TiMi Studios under Tencent, was released for iOS and Android on October 1, 2019.
The series became a major industry talking point when Microsoft announced its acquisition of Activision Blizzard in January 2022. The acquisition closed on October 13, 2023. Sony worried that Call of Duty would become an Xbox exclusive, but Microsoft promised to keep releasing it on other platforms through 2033.
Wikipedia describes the series as having earned $30 billion in revenue through 2022, making it the most successful video game franchise created in the United States. It has also expanded into action figures, card games, comics, and more, and Paramount Pictures is developing a film.
How to Play Today
As of October 2026, the main games you can play are:
- Call of Duty: Black Ops 7: The latest entry, released on November 14, 2025, for PlayStation 4 and 5, Windows (Steam, Battle.net, Xbox app), and Xbox One and Series X/S. It's also the last entry to release on PS4 and Xbox One.
- Call of Duty: Modern Warfare 4: The next entry, scheduled for release on October 23, 2026. Starting with this game, the series will no longer release on PS4 or Xbox One.
- Call of Duty: Warzone: A battle royale you can download and play separately without buying the main game.
- Call of Duty: Mobile: Playable on iOS and Android.
- Modern Warfare Remastered: A remaster of the 2007 game by Raven Software, released standalone in 2017 for PS4, Xbox One, and PC.
If you want to see where the series began, try the campaign in Modern Warfare Remastered first; if you want to experience modern multiplayer, starting with the free Warzone is the low-commitment option. Since the series deals with real war and violence, it's a good idea to check each game's age rating before buying.