Alan Wake 2 fan notices a sound cue gives the game away about its villain early on, Remedy sound dev gasps 'Finally someone noticed'
Surely the best kind of easter egg is one that gives the whole game away ahead of time, but which you'd never notice on your first time through. Baldur's Gate 3 does it with its music, BioShock did it with its revive system, and, hey, I guess Alan Wake 2 did it as well. Spoilers ahead for, you guessed it, Alan Wake 2.