I had a similar moment as Jinx in OoT. I was terrified when I woke up and saw Hyrule the way it was and I was also pretty young so it had a big effect.

FFIX was a whole "whoa" moment for me and what RPGs could be. It really got me in the the genre.

Tales of Xillia at the big moment when (SPOILER)you find out the Lance of Kresnik is not what you thought it was at all and this whole new chain of events unfolds

I have more but these are the ones I can think of right now