2. The Secret Rebecca Chambers Photo - Resident Evil 2
This Easter egg is admittedly more insanely specific than it is particularly elaborate, but it's tough to imagine how anyone without a debilitating case of OCD happened to stumble across it organically.
In the original version of Resident Evil 2, players who search Albert Wesker's desk in the S.T.A.R.S. office 50 times will be rewarded with a picture of the series' plucky medic Rebecca Chambers, kitted out in a cute basketball outfit.
Quite how anyone figured this out for themselves is beyond comprehension, and it wouldn't be remotely surprising if Capcom themselves eventually leaked the solution online.
Amusingly the Easter egg re-appears in the recent remake, though the method for obtaining the Rebecca photo is a lot less ridiculous - even if the game oddly decides to give her a more suggestive pose this time around. Oof.