When developers create their games, they have full creative freedom over what goes in and what stays out. Because they have memories, relationships, and inside jokes like anyone else, many of these things can bleed over into their projects and be hidden deep within the game's code.

We've seen this time and time again from numerous developers. They each put together a collection of easter eggs that are then sprinkled throughout each game. It's up to us to perform a complicated set of actions or search in the deepest corners to find them. Allow me to be the first to say that finding some of these are extremely difficult.

However, it's not all impossible and there are ways to unearth the biggest secrets a video game has to offer. If you're not great at that, then I suggest you read further to figure out how to find 15 well-hidden easter eggs that the developers never want you to see.

15 Calendar Man - Batman: Arkham City

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Rocksteady has been known for putting a lot of easter eggs in their games. There was a map of Arkham City in Arkham Asylum as well as numerous teases to Arkham Knight hidden within Arkham City.

Many of these teases were extremely obvious, such as Azrael or the Scarecrow easter egg. However, the most difficult one to unearth comes from Calendar Man. Every time you visit him, he says a different line. However, if you set your console's clock to December 13th, 2004 (years before Batman Arkham City) ever came out, Calendar Man gives a line about Batman's beginning and end. Considering that Arkham Knight was on its way, that was a chilling thought. The date is also significant as the day Rocksteady was formed.

14 Cracking The Everstone - Magikarp Jump

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It seems that every time a silly Pokémon game makes its way to mobile devices, people are going to start talking. Case in point: Magikarp Jump. This title has you raising a Magikarp through feeding and exercising so that it can jump higher than every other Magikarp in existence.

While the game focuses on the little karp itself, there is a way you can get Gyarados in the game. If you tap Magikarp enough times (it could take an excruciating amount of time), you will receive a notification that its everstone cracked and broke. Pokemon fans know that this object prevents a Pokémon from evolving. From there, level your Magikarp up to twenty and watch it evolve into the mighty Gyarados, which unfortunately, can't compete.

13 Green Hill Zone - Sonic Adventure 2

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Sonic Adventure 2 was well-known for being a solid jump from 2D to 3D for SEGA's mascot. It involved numerous levels across six different characters that each awarded you with a rank and medal for completion. Why is this important? Because it's how you'll gain access to the Green Hill Zone level.

In order to get this level, you must complete every level for every character (and that includes the time trial, collect the rings, find the chao, and hard mode variants) and receive the "A" rank on all of them. Sounds easy enough, but considering how difficult some of those levels are to beat, let alone get a good rank, you'll be playing for months just to see a 3D take on a classic level.

12 Teen Wolf - GTA V

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This is probably one of the most difficult easter eggs to pull off. In GTA V, there are special plants that can cause you to hallucinate and turn into an animal to explore the world. Apparently, dataminers found locations to plants that no one had ever found before. Instead of just searching the game with the coordinates, you have to manually look at them in the game's code to get a hint.

In order to complete the next few steps, you have to beat the game, find all of the peyote plants, and complete the Bigfoot quest. Then you can play as Bigfoot. But it doesn't end there. Afterward, you unlock a mission where you can hunt down Michael J Fox's character from Teen Wolf as Bigfoot. Once you do that, you can play as him in the game.

11 Secret Levels and Good Ending - Oddworld: Abe's Exoddus

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The developers of the Oddworld games love screwing with their players. If you haven't played one of their games before, then I suggest you start with Oddworld: Abe's Exoddus. It is the pinnacle of everything Oddworld Inhabitants does with their games and that includes packing in tons of secrets.

In the game, there are two endings depending on how many Mudokons you save: the good and bad ending. You have to save a lot of Mudokons to get the good ending, which, considering how tough the game is, isn't an easy task. A lot of them will likely die or be forgotten, which means you have to rely on the secret areas in the world to find more. But these areas are fairly difficult to find and even tougher to complete. So good luck getting that good ending.

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There was a contest ran long ago for whoever could find and take a picture of the Warmech from Final Fantasy. The winner was promised that their name would be placed in a future Nintendo game. Chris Houlihan won, and his name was placed into The Legend of Zelda: A Link To the Past. But good luck finding it.

The only way to access this room is by rushing from one to the next, making the game confused about which place it needs to load. When this occurs, you'll be transported to Chris Houlihan's secret room, which contains a clever line of dialogue and 45 rupees for your troubles. You don't get anything else for actually breaking a Nintendo game. Congratulations, I guess?

9 The Tedious Sidequest - Final Fantasy IX

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Each Final Fantasy game incorporates a number of sidequests and missions to keep feeling expansive and fresh all of the same. However, there was one quest in Final Fantasy IX that wasn't completed until 2013: 13 years after the game was released! Thankfully, the secret has been discovered and it's no wonder why it went unnoticed.

In a destroyed city, a character will run out of their homes stating that their brother had gone missing. From there, most people just carried on and lamented how they never found the missing brother. Actually, what you are supposed to do is fight the next boss then travel back to this area a total of ten times before you can go into the house and get some items that aren't worth your trouble. Welcome to RPGs.

8 Mew- Pokémon Red And Blue

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When Pokémon Red and Blue were being developed, so much space was taken up on the Game Boy cartridge that there was almost no room for anything else. Yet, one developer noticed that there was just enough space to insert another Pokémon, and then he put Mew in the game. Yet, there was no way to acquire Mew, as there was only space for the character itself.

That didn't stop people from finding a way, though. It requires that you glitch a trainer battle and travel to a specific piece of grass. It's fairly long, so you'd do best to look it up on YouTube. Thankfully, if you pull this off properly, Mew will level up to 100 after you give it a little bit of experience. That has to be worth it!

7 Secret Message - Halo 3

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Just like Batman: Arkham City, even the legendary Halo 3 had its own easter egg that wasn't discovered for a really long time. In this case, it took seven years before anybody discovered it. So don't expect to see any special skulls or Hayabusa armor on this list.

If you click on the sticks during the loading screen, it normally won't do anything. If you perform this action on Christmas Day, however, you'll get a secret message that pops up. What does something so elusive say, you might ask? "Happy birthday, Lauren." I kid you not. We went seven years in the dark to only find that we weren't missing anything at all, other than Bungie's love for some woman named Lauren.

6 Samus's Ship - Donkey Kong Country Returns: Tropical Freeze

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After Donkey Kong 64 and the departure of Rare, Nintendo chose not to make a proper Donkey Kong Country game until Retro Studios (the developers of Metroid Prime) were willing to take it over. The result was the Donkey Kong Country Returns series.

As you might expect, these games hold a few references to other games from Nintendo, and more specifically, games that Retro has worked on. One level in Tropical Freeze places every character and object in the foreground in a silhouette. This makes it difficult to spot things in the background as well, but the perceptive eye will notice that Samus' ship has crashed in the jungle and is tangled in the trees. For those of you that thought this was a tease of Retro's next project, you'd be wrong.

5 Plot Reveal - Dead Space

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Dead Space is one of the most horrifying games ever created, putting you in the shoes of a man who is scared, desperate, and isolated. For those of you that don't know, the entire purpose of him being there is to find a woman named Nicole. As you might know by now, she is revealed to have already been dead.

Yet, the game actually unveils this to you before you even get to that point. Every chapter in the game has a title and if you place the first letter together, it spells out the phrase "Nicole is dead." Those that were really paying attention would have to worry about spoilers, though they probably wouldn't put it together until fairly late in the game.

4 Slenderman - Runner 2: Future Legend of Rhythm Alien

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A game like Runner 2 is difficult to put easter eggs in that aren't just costumes. Because the game is so fast-paced, you have to focus on Commander Video and what is immediately happening around him before scanning the background. Thankfully, there are some who are capable of this and they found an interesting secret.

In one of the levels, you might notice a strange figure in the background. Fans of the horror genre will immediately recognize this figure to be the frightening entity known as Slenderman. While he doesn't do anything in the game, it's a cute little nod to a franchise that is now dead in the water. If you ask me, he should end up being a new killer in Dead By Daylight.

3 Pupu - Final Fantasy VIII

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There are a ton of things to do in Final Fantasy VIII. Whether it be looking for the Jumbo Cactuar on Cactuar Island or traversing a mysterious tower just to get a chance at recruiting Odin to you team, there are plenty of things to keep you busy in that game.

One of the more frustrating sidequests is the one involving the creature known as Pupu. You can't just find it in the overworld, you have to trigger it. You do this by scouring magazines for a special hidden one. From there, you travel to four different locations to encounter the Pupu UFO. It isn't until the last time that you actually get to fight the creature. Oh yeah, if you want the Pupu card, you have to give the critter five elixirs. The card isn't even that good, but there's no other way to get it.

2 Play as Master Hand - Super Smash Bros. Melee

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I remember the days when many secrets were talked about for Super Smash Bros. Melee. There were some people who stated Sonic was a secret character in the game. Others said that you could evolve Pichu into Raichu. Yet, among all of the fake crap, there was a real easter egg that allowed you to play as Master Hand.

As it stands, this is more of a glitch, but something extremely fun to accomplish. It involved pressing a complicated set of buttons on the GameCube controller then making sure that you're plugged in to the third slot on the console. If done properly, you'll play as Master Hand, who is horribly broken and OP. If you win with him, though, the game will crash.

1 Everything Story Related - Black Ops III Zombies

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A mode that started as an easter egg itself has now expanded into a massive story that requires easter eggs in each map to understand what in the world is going on. As many of you know firsthand, these easter eggs are some of the most difficult and tedious things to do in the history of Call of Duty.

Most of them will take you half an hour at the very least and require a specific and complicated set of actions to do. You also have to watch your back though, as there isn't a surefire way to do it without having a horde of zombies (or at least one sprinter) chasing you the entire time. Furthermore, many of the easter eggs require having a team of four people, which is hard enough to acquire on its own.