In the current gaming climate, secrets in video games rarely stay secret for long.
From the moment of release, titles are scoured by determined YouTubers and completionists, all desperate to be the first to find every hidden treat, in pursuit of being the first to see something, or perhaps a retweet from the developer if they're exceptionally lucky.
However, in the days before social media, video game experiences were generally the personal business of the players. Nobody was so intent on discovering a game's secrets, that they would frequently go undiscovered for years or even decades, being stumbled upon by complete accident or even revealed a long way down the line by the studios themselves.
These impressively buried easter eggs can come in the form of hidden quests, entertaining in-jokes or even areas and pieces of code seemingly not intended from the finished product, but left in as a result of developers simply finding it easier to disable their access rather than remove them entirely.
It's not out of the question that this is still happening, and in 20 years time an ageing Rockstar programmer may well reveal through neo-Twitter that shooting exactly the right pebble with a small arrow by the Elysian Pool in Red Dead Redemption 2 will reveal Arthur's trusty steam-powered jetpack.
Until then though, the following are pretty damn cool.
10. Developer Credits - Donkey Kong
Here it is, one of the earliest known Easter eggs in gaming (if not the outright first). The reveal of a secret hidden in the Atari 800 port of seminal Nintendo hit Donkey Kong may seem underwhelming today, but speaks to a bygone era of gaming worlds apart from what we have today.
Programmer Landon Dyer had designed the port almost entirely by himself, with no support, existing code and little hope for a licencing deal. Because of this, he opted to hide a little secret in the game's code - something that wasn't known until he revealed it himself 26 years later.
After the code was picked apart and the secret's conditions revealed, including reaching a very specific high score, losing all remaining lives in a certain way, setting a particular game difficulty and sitting through the demo screen, the Easter egg was finally revealed:
The letters "LMD" would appear near the bottom of the title screen. A little disappointing these days, when Easter eggs can be anything from playable characters to entire hidden missions, but considering the limitation of memory on such early platforms and the lack of credit developers were afforded at the time, you can't expect much more.