While most Easter eggs are found within a matter of days or even weeks after a video game’s release date, some secrets have taken much longer to reveal themselves. Here are 10 video game Easter eggs that took years to discover.  

1. GOLDENEYE 007 (1997)

GoldenEye 007 is considered one of the best first-person shooter video games of all time. Though many of its secrets were found upon its release in 1997, a computer engineer with the username “spoondiddly” discovered a pretty big Easter egg 15 years later. Buried deep inside the game’s code, there’s a fully functional emulator with 10 playable games for the ZX Spectrum system (UK’s version of the Commodore 64). Now you can play games like Lunar Jetman, Gunfright, and Knight Lore inside of GoldenEye 007.

The company that developed the game, Rare, was tinkering around with system emulation for the N64, which was a new console at the time. Instead of removing the emulation, Rare just disabled it with a patch. However, spoondiddly discovered how to re-patch it.

2. THE LEGEND OF ZELDA: A LINK TO THE PAST (1991)

In 1990, Nintendo Power hosted a contest where one of its readers' names would appear in an upcoming SNES video game. A reader named Chris Houlihan won the contest, so Nintendo programmers named a secret room after him in The Legend of Zelda: A Link To The Past. The room remained hidden for 10 years until gamers started to pick apart the game’s code in 2002.

Gamers can find the room using the Pegasus Boots in a series of dashes from the Sanctuary to the Sewer Passageway's entrance. If done correctly, the secret room will reveal itself. Once inside, Link will be greeted with the name of the room and 45 Blue Rupees.

3. DONKEY KONG (1983)

In 1983, Atari hired video game programmer and designer Landon Dyer to port Donkey Kong from the arcade to the Atari 400/800 home consoles. After he finished writing more than 25,000 lines of assembly code, Dyer hid his initials “LMD” deep inside of the game. It remained undiscovered until an engineer named Don Hodges figured out how to unlock the Easter egg 26 years later in 2009.

Here’s how to find Dyer’s initials: First, set a new high score between 33,000 and 33,900 points. Then kill off all your remaining lives, but save the last life to be killed off by falling off a really high girder. Afterwards, press the “Option” button three times to set the game’s difficulty level to 4. This will unlock the game’s credits page and the programmer’s initials, “LMD.”

4. WAVE RACE: BLUE STORM (2001)

Released in 2001, Wave Race: Blue Storm was a hit jet ski racing game for Nintendo’s GameCube. Although a majority of its secrets were revealed throughout the game’s initial release, it took gamers almost 10 years to discover an Easter egg hidden deep in its audio settings menu. Once unlocked, the normally upbeat and enthusiastic announcer will be replaced with a bored and sarcastic one.

Here’s how to find the Easter egg: Go to the audio settings menu and tap “Z” until the waveform on the page looks like rising fog, and then use the D-Pad to type in “Up, Up, Down, Down, Left, Right, Left, Right, A, X, and Z.” You’ll then hear an audio cue if you entered the code in correctly. Start a race and pick the first racer to hear the voice of the new announcer.

5. SUPER SMASH BROS. MELEE (2001)

Seven years after Super Smash Bros. Melee was released for the GameCube in 2001, an Easter egg was discovered to unlock the game’s final boss, Master Hand, as a playable character. The player has to perform a very elaborate combination of inserting controllers and some well-timed button pushing, but the end result will have you dominating every character in the game.

Here’s how to unlock the character: First, connect a controller in port three of the GameCube, then go to the character selection screen in the game. Select an opponent and then select your character as “Human.” Instead of selecting a character, clear all the names in your list except one (this will be the new option for Master Hand). Now position your cursor on the entry box to select a name, but instead press “A” and “B” at the same time. Continue holding “B,” but let go of “A” for a split second and then press “A” again at the exact same time the character selection screen exits. If done correctly, the game will take you to the setting location screen where you can now pick any location to play as Master Hand.

6. BATMAN: ARKHAM CITY (2011)

In 2011, video game developer Rocksteady Studios included a secret message inside of Batman: Arkham City that revealed hints and clues surrounding its sequel, Arkham Knight. The Easter egg remained hidden for three years until Rocksteady released how to unlock it in a YouTube video in 2014. If you set your Xbox 360, PS3, or PC's clock to the date December 13, 2004, Calendar Man will give a monologue about being there “from the beginning," and will warn you that "the end of days is coming." The special date in 2004 is when Rocksteady Studios was established.

7. PUNCH-OUT!! (1987)

In 2009, late Nintendo president Satoru Iwata revealed a visual cue in Punch-Out!! to knock out Bald Bull during the first fight. When a camera flashes on the right side of the first row in the crowd, that’s the exact moment to throw the knockout blow. Iwata revealed the Easter egg 22 years after the boxing game was released.

Earlier this year, a similar Easter egg was also revealed that clued gamers in on how to knock out Piston Honda during the first World Circuit bout. When the bearded man on the left side of the first row ducks down, that’s the exact moment to throw a punch to knock out the Japanese boxer. 

8. FINAL FANTASY IX (2000)

Since it was released for the original PlayStation in the year 2000, gamers have unlocked most of the secrets and quests contained in Final Fantasy IX. However, the game’s final side quest was discovered 13 years after its release. The secret quest involved the Nero Brothers teaching Zidane how to gamble. Gamers had to track down and encounter all three brothers throughout the game on disc four, only to receive a Protect Ring once the side-quest was completed.

9. SPLINTER CELL: DOUBLE AGENT (2006)

While hardcore fans often find Easter eggs in video games within weeks of release, sometimes secrets are hidden so well that the game’s programmers have to come out and tell people how to find them. Take Splinter Cell: Double Agent, for example. It was released in 2006, but one of its Easter eggs remained hidden until Ubisoft released how to unlock a special baby seal rescue mission in 2010. The secret side mission must be found in co-op mode and involves an elaborate series of finding coins in the right order to use in various vending machines to rescue five seals wearing party hats with the names Muffin, Pepperoni, Vanilla, Cookie, and Buddy.

10. HALO 3 (2007)

Although Halo 3 was released in 2007, a special message from the game’s developer Adrian Perez to his wife wasn’t discovered until seven years later in 2014. Halo modder Lord Zedd found the secret after a game engineer revealed there was only one more Easter egg that remained hidden during a fan Q&A in 2012.

If you press down both thumbsticks during the game’s loading screen on December 25, it will reveal a wider look at the Halo ring with the message “Happy Birthday, Lauren!” inscribed on it. The Easter egg is only available to view on December 25, or if your Xbox 360 or Xbox One’s internal clock is set to the date.