Call of Duty is one of those games that nearly every gamer has tried. A huge success, the series has been delighting armchair marines for years. And there is simply no better way to spend an afternoon than being verbally abused by an eight year old while trying for a streak. Anyone who has played the games for longer than two minutes knows what we’re talking about. In fact, if you really want to be entertained, the various 'rage' videos that have been posted on YouTube are a heap of fun. Audio recordings of those eight-year-olds threatening to end your mother because you shot their video game (as in not real) soldier just don't ever get old.

But we digress. Call of Duty also has a ton of interesting trivia and secrets attached to it too. We've managed to dig up a treasure trove about the series that should do one of two things. It will either make you laugh and want to play the game later (because it's such a heart-warming family game that you can play with your loved ones) or cry as you bemoan the state of the youth of today. We think it’s a list that may tell you something new here and there too. The game has a rich history in the campaign levels. On a serious note, the following list has some rather unpleasant entries. And the entry at number three is truly awful. Please don't say we didn't warn you.

20 The Homophobic Easter Egg

Call Of Duty: Modern Warfare 2 was an incredibly popular title, and it's still looked back on with fondness by all those little kids who've now grown up to be adult gamers. Full of exciting scenes and huge set-pieces in the campaign, it was one of those titles that helped to define not just Call of Duty, but first-person shooters in general. Everyone liked it.

Except people who were gay. Jokes about gay people are not cool in any context, ever. But in a video game that was played by millions of kids around the world, it was even worse. We won't detail the full verbal exchange between two soldiers in the game, but it's enough to say that one soldier asks another if he is "still gay." It was disgusting, dumb, and it probably made millions of ten-year-olds laugh.

19 Grenade Spam

Grenades (or 'Nades' if you're the kind of person who plays video games too much and wants to cut down her use of words due to time constraints) have been a pain in most Call of Duty games since the very first one came out. At some point players will start crying and screaming that grenades are either too powerful or too abundant. And by 'abundant' we mean they're flying at you from all directions for every single second of the game.

The new Call of Duty: WWII game has reignited the crying and is already proving to be a thorn in the game developer's sides. Funny that, in the real WWII, no soldiers whatsoever were running around screaming that 'the 'nades need to be nerfed'. That's probably because they were too busy insulting each other's moms while doing a '360 no-scope' type of thing. Before being shot.

18 The Magical, Mysterious, And Missing Favela Map

This was a major mess. In Call of Duty: Modern Warfare II gamers could play on a map called Favela. It was a great map and players loved running around and shooting each other in the face before they went to school. Fun times for all involved. However, Favela was taken down and has never been seen since (unless you are lucky enough to find a server that still has a version of it).

Favela was removed because in a bathroom on the map, players could look at a picture hanging just above the toilet. In the picture you see a tree. However, on the outside of the frame, running along the whole edge, is an Islamic quote. The picture was above the toilet, which is believed to be disrespectful in Islam. Infinity Ward removed the map as soon as people complained.

17 The Airport Scene

Anyone who has even the slightest interest in Call of Duty as a series of games will know about the level called 'No Russian'. This was in Call of Duty: Modern Warfare II. If you were completely innocent as regards the content of the level, you'd probably find that it started like any stage, with you being given orders and walking into an area.

That area, though, is an airport packed with civilians. In the mission, you are told to follow the lead of the head of the group. With their guns, the group promptly start ending the lives of all the civilians. You have a choice, and can skip the level at any point, and you can complete the level without firing a bullet. But it is one of the most controversial levels in gaming because of what it shows.

16 The Southern Scene

Back to Call of Duty: WWII, and in part of the game (set, naturally, in World War II) you actually see two French people on trees. It's a truly horrible sight, and gamers were quick to criticize the developers. The game has an age rating, but still gamers thought this was going too far. And the media joined in too. At one point it was compared to the treatment of black people in the Deep South.

Activision published the game, and they went on record stating, the scene was accurate. That it certainly was. The M rating the game has should keep anyone under the age of 17 away from the title, but we all know who the players are. So, Activision just succeeded in showing millions of ten-year olds what this looks like. Great.

15 Shock And Awe, And The End

Call of Duty 4: Modern Warfare is a landmark title in the series, and is widely regarded as one of the best COD games ever. During one of the campaign missions (Shock and Awe) your character manages to board a helicopter to escape the area. Then there are ominous warnings over the radio about a nuclear capability in the area you've just left behind.

Before you can process what was said, an explosion occurs, and the screen shows the immediate effect of a nuclear blast. Then you're forced to the ground and the nuclear blast is witnessed in all its terrible glory. It's seen by some people as a magnificent spectacle, and others as simply disturbing. By the time it's over, 30,000 soldiers have died. It’s not a particularly cheerful moment.

14 When Trolling Goes Horribly Wrong

Trolling (or the art of being annoying and vindictive during game time) has often ended up causing rivalries and other social problems offline. However, one time it really went overboard, when a 46 year-old man became so irate at the trolling he was receiving from a 13 year-old player he went round to the boy's friend's house and strangled him. Thankfully, the boy survived.

Mark Bradford (the grown man) had been playing against a team that included the young boy. The boy had been goading him (not an experience that is unfamiliar to players) and Mr Bradford lost his temper. He went round to the house to deal with the situation.The boy suffered scratches and bruising. Kind of puts a whole new perspective on those trolling videos on YouTube, doesn’t it?

13 Animal Rights? Never Heard Of It!

Call of Duty: World at War had plenty of nasty things happening in it. The games are renowned for rewarding headshots and killstreaks, so no one really plays them expecting gameplay that is pleasant and relaxing. Animals featured in Call of Duty: World at War. Attack dogs.

Players had to hit them to stop the attack. Animal rights activists and bodies, quite rightly, felt very strongly about this. There's no choice involved; players have to do this to the dogs to survive. This all resulted in animal rights groups organizing a petition against the game, and PETA making a media statement about how awful it was. Oh, and it didn’t help that particularly skilled players could trigger their own pack of attack dogs, either.

12 Plenty Of Blame To Go Around

Anders Breivik wasn't the only deranged monster to be allegedly influenced by Call of Duty. Mohammed Merah went on a bender in the southwest of France, ending the lives of seven people, including children. All of this happened in a Jewish school in Toulouse. Three other victims were soldiers and one was a Rabbi.

Merah had a wife, and after the atrocity had occurred she told the international media that there was one game in particular he liked to play on his PlayStation. In fact, she made it clear that he played a lot of Call of Duty before he ended the lives of those seven people. She said: "We had many religious conversations, but we spent our time playing PlayStation, including Call of Duty."

11 When It Tried To Carry Out Foreign Policy

Okay, maybe we're talking covert US foreign policy, but having a level that basically depicted an event that the US had tried to make happen, to no avail, wasn't the best way to play it. In Call of Duty: Black Ops you enter the bedroom of Fidel Castro and end him. It's nothing special, just another show-down in a Call of Duty game, but perhaps unsurprisingly, the Cuban government took offence.

The Cuban government said that: "...what (the US government) couldn't accomplish in more than 50 years, they are now trying to do virtually." In normal speak this translates as the US government consulted with the game developers to show a US President's fantasy sequence. There were no further repercussions, but it was extremely embarrassing for Activision.

10 UK Parliament Outraged

Now, it usually takes a lot to find yourself being discussed in the UK Parliament. But Activision found that it doesn't take as much as you think. In Call of Duty: Modern Warfare 3 the game depicted an attack in London. It was horrible, and showed uncomfortable stuff. There was even a scene with a child in peril that made some players feel a little ill.

However, it was when the game took players to the London Underground that MPs in London began to get upset. They compared it to events in 2005, when London came under terrorist attack. Parliament heard MPs state that they wished to complain about the game, which showed "violence against members of the public." Again, no action against Activision, just more embarrassment.

9 Don't Mention The War In Singapore

All that controversy obviously deeply affected Activision, which took note of the problems and the hurt caused. They decided to just continue making more games that featured scenes of questionable taste. But to be fair, it wasn't the game itself that caused controversy in 2015. It was the marketing that the company launched before the game had even hit the shelves.

Call of Duty: Black Ops III featured an attack in Singapore. Now, obviously this was a disturbing and alarming event, and thank God it wasn't real. Oh, wait, Activision decided to scare everyone on Twitter with fake news updates about the attack. the news updates were provided by "Current Events Aggregate" and they were scarily realistic. The whole thing was terrifying, and many Twitter users complained. Sales of the game, naturally, set new records.

8 Making Real People Look Bad

In Call of Duty: Black Ops II, there was a particular conflict that the developers decided to feature. Remember that Fidel Castro thing? Not a one-off. In this game they featured an Angolan rebel leader called Jonas Savimbi. Jonas was a very controversial figure when he was alive, and was involved in a number of missions and incidents that involved the ending of many lives. He wasn’t a pleasant man, according to reports of the war.

Activision portrayed him in a way they thought was sympathetic. However, Savimbi's family were not happy. His surviving children mounted legal action against Activision, complaining that he was instead portrayed as a barbarian. Activision must have been pretty unfazed, considering they seem to have annoyed and/or upset nearly everyone on the planet at this point in the series.

7 The Pointless Scene In Every Game

To be honest, Call of Duty has a number of awful scenes in it, spread across the whole series. But every now and then it goes even further, bringing you a scene in the campaign that just leaves a nasty taste in your mouth. You see, Call of Duty seems to revel in players committing horrible acts at key points in the campaign levels. It's a common theme, and it has meant that some games go way over the top.

There is a scene in Call of Duty: Black Ops that involves a man tied to a chair (a common sight in these moments) and interrogated. One moment has in it a shard of glass unhelpfully in a character's mouth and some dark humor that makes you glad it's just a game. Sometimes games can take it just too far.

6 How About Plagiarism?

Yes, Call of Duty even ripped off someone else's work (allegedly). When the brand new title, Call of Duty: WWII was released, it took precisely six seconds before fans noticed that the cover art for the game looked very much like the cover art for another game. That other game wasn't released at exactly the same moment, so a coincidence was ruled out. Bummer.

The game was Brothers in Arms, and it was a pretty successful title from back in 2008. Activision must have thought that 9 years was enough of a time period for gamers to forget about the older title. They were very wrong. Multiple complaints ensued on every social media platform under the sun. It got worse when some players noticed an even bigger similarity with a limited edition version of Brothers in Arms.

5 Did You Know That Your Controller Was Funeral Compatible?

Call of Duty: Advanced Warfare (which is probably the most hated title in the series) did something that angered pretty much everyone. The scene in question involves no bullets, and no war action at all. It's hard to believe unless you actually play the game, but we'll try and describe it for you.

At one point in the game you're laying your friend to rest in Arlington Cemetery. Then suddenly you're asked to 'pay your respects' to the fallen buddy. But it doesn't just ask you, you actually have to press a button, as if it were some super weird first person shooter that absolutely no one liked (oh... wait a minute). Seriously, pressing a button on your controller to facilitate a funeral is bizarre. Most fans thought it was ridiculous, while some thought it was very respectful. Activision simply gained publicity.

4 The General Who Betrayed You

Let us head back in time to Call of Duty: Modern Warfare 2. This was an entertaining title, and contained many an engaging plot point. There was a lot going on, but all the while, you knew that General Shepherd was there, watching your back, making sure the missions were completed. He was an all-round good character who you knew was in it for the honor and the pride.

Except he wasn't. He was the 'big twist' in the game, and at the end he reveals himself to be the traitor of the story. Players cried out 'no!' all over the globe when they reached this point in the game (or at least we did). Oh, and Shepherd also ends the lives of Ghost and Roach. Just in case you thought it was a double twist.

3 The Edited Scene You Won't See

Call of Duty has arguably pushed the envelope consistently, in an attempt to make the experience for players more 'real' and challenging. It's how the games keep their edge, and even while they may upset players, most of what happens can be justified by the fact the games are set in a war situation. In Call of Duty: WWII everything became a lot harder to justify.

In one scene, your character interrupts the interrogation of a woman by a soldier. If you leave them to it, it's made pretty clear that the soldier is going to assault her in the most  degrading way possible. Except that now the scene is different. Certain sounds aren't heard and the woman is dressed in pants and not a skirt. Activision changed the scene after complaints.

2 The Missing Symbol

Call of Duty: WWII is the latest game in the series, and it has caused problems everywhere. Whether it's insensitive to history or being bad to women, it has seemingly been created to anger and amaze in equal measure. But one of the most controversial aspects has nothing (directly at least) to do with tragedy.

The game doesn't feature the symbol of the major bad party of World War II. Instead, it shows the Iron Cross on flags and other regalia. Some people think it's an attempt to avoid controversy. Others think that it shows some kind of tolerance and inclusivity. Actually, to show the symbol in a game is illegal in Germany, which would have meant a huge fall in sales.

1 The Training Routine

Anders Breivik is a seriously disturbed man who, one terrible day, went out and ended the lives of 69 people in Norway. The atrocity was carried out entirely by Breivik, and he is now in prison. His lifestyle just before he committed the attacks was almost solely dedicated to gaming. At one point, he was spending 16 hours a day playing a game called World of Warcraft. This huge fantasy RPG has been linked to nasty people before, but it wasn't Warcraft that affected Breivik.

Anders Breivik was a huge player of Call Of Duty. The famous first person shooter title has consistently been blamed for antisocial behavior, but Breivik (allegedly) used it to train his shooting skills. Using the holographic sight on one of the in-game weapons, he apparently enhanced his shooting skills.