I was on the other side of this, playing Castlevania Symphony of the Night in elementary school. One day I discover something that my friend never found, even though I looked up him, since he completed the whole game.

Well what I discovered was the reverse castle and another 50% of the game he never played. I called him on the landline and started telling him about it and he was saying "what are you even talking about", he thought I was lying until he followed my instructions.

That thing settled exploration as one if my favorite thing in videogames, the discovery was amazing