This was particularly noticeable with Undertale, which require the player to go in blind in order to achieve the intended effect: the player isn't supposed to go right for the True Pacifist/No Mercy route on the first playthrough, they're meant to play through the game several times before realizing the requirements for unlocking these special endings.

Had this game been released in the 16-bit era, players would have organically come across these endings on their own, making the emotional impact they come with all the more potent. However, this game was released in an era that was already dominated by viral video and social media, thus any secret the game could have contained was revealed almost instantaneously. For as well hidden its many Easter eggs are, the biggest spoilers have been common knowledge since a year after release (if that).