From leaving their initials written on the scenery to hinting at future games, developers will often place in-jokes and Easter eggs throughout their games, to surprise and delight players who are fortunate to come across them. From subtle nods to pop culture to glitches that became iconic and memorable, games are considered much better places to hide Easter eggs simply because it is totally up to the player to find them, as opposed to films where references are practically forced down the viewer's throat. However, some of these references and in-jokes are notoriously difficult to find, usually thanks to the intentions of the developers (sometimes they just do it for their own benefit and sometimes in pursuit of the distinct pleasure of them being left unfound) and can sometimes be overlooked. Thankfully, gamers are a lot more diligent than they used to be, and though casual gamers and those who don't fall under the completist banner will probably have never found the references and Easter eggs on this list, there are some out there who pride themselves on their in-game sleuthing skills. We salute them for their commitment, and for uncovering these gems. When you've finished reading this article, why not do something unproductive and pick up these listed games, replay them and find these references first hand.
10. Metroid - Passwords
Metroid was one of the first NES games to use a password system, common enough today but less utilized in the past, to allow players to access levels and weaponry at a time they had earned it rather than having to initiate the entire game from level 1 on every play through. The two significant codes - Justin Bailey and the Narpas Sword code - unlocked all the power ups needed to win the game in under an hour (though Justin Bailey didn't unlock the Ice Beam, and the other unlocked every weapon regardless of its practical use. What made these passwords so difficult to find was a literal fail-safe built into the game that rejected attempts to discover the passwords in the games code. Until recently with the expansion of the internet, they would be nearly impossible to use, and it has been suggested that the Justin Bailey password was actually only discovered by a complete fluke.