In 2003, a plucky new World War II shooter emerged from a little-known video game developers Infinity Ward, boldly claiming it could revolutionise the PC's first person shooter scene. Eleven years on and Call of Duty has done more than that, growing into a franchise capable of bringing in more cash than a summer of Hollywood blockbusters.
As we eagerly count down the days until its latest instalment Advanced Warfare arrives on consoles (that's 4 November, so still some way off), we dug through the treasure trove of facts, numbers and achievements that this beloved series has given the world of gaming. Grab a gun and prepare to learn something new about one of the most successful video game franchises of all time.
1. The forgotten handheld
From PC to next-gen console, the Call of Duty series has planted its boots on just about every gaming platform going. One of its more unusual (and little played) instalments was built for Nokia's ill-fated N-Gage mobile console system: the plucky mobile supported a single player storyline with multiple objectives for each level, while an 8-way multiplayer could be competed via Bluetooth. For a taste of the somewhat aged action, check out game's the trailer.
2. Blurring fiction and reality
Call of Duty has always strived to tell gripping, dramatic stories, with brutal characters portrayed by A-list actors. However, the realism of Black Ops II didn't go down well with everyone: in July 2014 lawyers of former Panamanian dictator Manuel Noriega launched a lawsuit against Activision claiming the title had used his likeness without authorisation. A 13-page document filed in Noriega's name claimed that he was portrayed as a "kidnapper, murderer and enemy of the state" responsible for "numerous fictional crimes" in Black Ops II. Previous lawsuits have been levelled against publishers when games borrow their likeness, but as Noriega isn't a US citizen it's unclear as to what legal grounds his claims have.
3. Sharp thinker
Fear you've fried your brain with one-too-many COD matches? Your lengthy sessions may have equipped you with some unexpected mental skills. A research paper published in Current Biology found that the decision making skills of 18 to 25-year-olds who played action-shooter gamers such as COD were faster than those of a group who had played strategic games such as The Sims 2. The high pressure scenarios and frantic action of the game's multiplayer resulted in non-gamer test subjects gaining noticeably faster decision making skills over the course of the study.
4. The cuddly stars
Only been a fan of the COD series since Modern Warfare? Where have you been?! As well as missing out on a multitude of great titles, you've also missed on many appearances from the series' main star - the humble stuffed teddy bear. First appearing in 2004's Call of Duty: Finest Hour, a multitude of internet rumours have sought to explain why a teddy bear is the recurring Easter Egg of the series. Some have posited that it's an in-joke introduced by Treyarch, having always including a bear in their titles. Others have taken the more apocryphal line of suggesting that a lead map designer lost his daughter to cancer while making the game, including her bear in her memory. Whatever it's origin, the teddy is one of the longest running Easter Eggs in gaming.
5. Propaganda cameo
From footballers to rappers, Call of Duty has attracted many fans over the years - but none quite so bizarre as Uriminzokkiri, a propaganda agency of North Korea. In 2013 the group produced a video following the dream sequence of a North Korean man envisaging a world torn apart by war. In order to depict he destruction of the USA, the video pinches footage of New York from Modern Warfare 3. Head here to watch the video, with the offending clip starting around 2:10.
6. A feast of numbers
Celebrating the launch of Call of Duty: Ghosts, Activision drew together a fact sheet of staggering figures to demonstrate the scale of the series' multiplayer dominance. Compiling data on every title since Call of Duty 4: Modern Warfare, 100 million players had notched up 32.3 quadrillion shots, collected 31 billion care packages and destroyed 5 billion cars in over 25 billion hours of game time. To put that into perspective, the US arms industry produces around 10 billion bullets a year, while five times the number of cars currently registered would need to be created, just to be blown up.
7. Eyes down
Another surprising talent you'll have picked up from Call of Duty sessions is an enhanced level of visual attention. Researchers from the University of Toronto found that after 2 and ten hour sessions on COD, test subjects who had not previously played video games noticed significantly improved skills in spotting target objects in cluttered visual scenarios. The researchers even picked up on changed brain wave activity in the participant as they learnt to pick out targets in the chaos of a COD deathmatch. Real-life applications of these improved visual skills include spacial awareness and driving - though we doubt you'll get a discount if you show your insurance group your K/D ratio.
8. The cancelled games
While a staggering 15 major titles have been released in the Call of Duty series, the list could have been longer still. Four Call of Duty titles never saw the light of day, some nearer completion than others. Call of Duty Tactics by Vicarious Visions lent a top-down strategy angle to the familiar WWII setting, while Call of Duty: Devil's Brigade saw players return to WWII for a third-person shooter. Call of Duty: Combined Forces was set to be the sequel to Finest Hour, but was canned after costs were felt to be too great. Sledgehammer Games' Call of Duty: Vietnam was also put on hold indefinitely after the team joined Infinity Ward to assist with Modern Warfare 3 - we'll get to see their own take on Call of Duty with the forthcoming Advanced Warfare.
9. The Call of Duty card game
Another iteration of Call of Duty that never saw the light of day was an inspired card game by Upper Deck Entertainment. The two-player game would see opponents deploy three soldiers to the battlefield from a 'squad deck', before drawing action cards to determine what their soldiers would do in the field. Despite drawing considerable attention with their working demos, Upper Deck Entertainment cancelled the project before its release in autumn 2008. You can see it in action here.
10. The game that inspired Call of Duty: Black Ops 2
While Call of Duty failed to get its own table-top game, another board game did serve as inspiration for the radical overhaul of the Black Ops 2 multiplayer. In an interview with Polygon, game design director David Vonderhaar revealed that a conversation about the tile game Carcassone led his team to come up with a 'Create-a-Class' board game idea. They soon had their developers attempting to build load outs of guns and skills out of decks of cards, which in turn led to the pre-match menu system that would appear in the game.
11. A session to remember
Ever pulled a COD all-nighter? Then you know something of the pain experienced by Okan Kaya, who in November 2012 set a new world record for the world's longest marathon gaming session at 135 hours and 50 minutes. The 28-year-old Australian was allowed to take a 10 minute break for every hour of play, fuelling his session on snacks and energy drinks. As the Guinness World Records rules allowed for the breaks to be accumulated, Kaya was able to bank up several hours for a quick sleep. During his epic session, he rose to 37th place in the Black Ops 2 leaderboards - and went through several packs of plasters in an effort to protect his thumbs and trigger fingers.
12. A record setting series
Since Call of Duty 4: Modern Warfare, every entry in the Call of Duty series has claimed a spot in the top 40 best selling video games of all time. The highest entry to the list is 2009's Call of Duty: Modern Warfare 2, claiming the 9th spot with total sales of 28.5 million. To date, the series has sold over 140 million copies, making it the 10th best selling franchise of all time (though still some way behind a certain Italian plumber's legacy of 445 million copies).
13. The Chinese exclusive
While the majority of Western gamers will pour hours into Call of Duty's many console and PC multiplayer experiences, things work a little differently for the Chinese market. Hosted by the Chinese online social gaming network Tencent, Call of Duty Online is a free to play title exclusive to mainland China. Drawing on dozens of maps, weapons and character models from the Modern Warfare and Black Ops series, players are able to modify their characters, weapons and uniforms with a variety of micro-transactions available through the in-game store. It even has its own exclusive Zombies mode, Cyborg Rising.
14. The Special Edition Jeep
From night vision goggles to radio control cars, limited edition and collectors edition Call of Duty titles have included some pretty spectacular items of memorabilia. The most unusual piece of merchandise to date is undoubtedly Jeep's series of special edition Wranglers - including 2010's Wrangler Call of Duty: Black Ops, 2011's Jeep Wrangler Call of Duty: Black Ops Edition and 2012's Wrangler Call of Duty: MW3 Special Edition. Featuring the title's respective logo on their roof, front panels and throughout their interiors, astonishingly none of the Jeeps came with a copy of the game.
15. A lengthy cast
While much of the focus of recent Call of Duty games is given to its multiplayer game modes, the series has played host to a wide number of campaigns and stories. Staggeringly, 124 playable characters have appeared in the series - from Logan Walker to Richard Nixon. We got to 32 before we gave in and had a look at the complete list.