For me, that moment was in Kingdom Hearts 2. I hadn't played the first game (or the second game) and didn't really understand the concept of sequels that continued a story. My parents had gotten me the game probably because it had Disney characters in it. But this moment stuck with me nonetheless.
It was the game's first boss fight, the Twilight Thorn. Everything leading up to it and the fight itself was just utter cinematography to my young eyes. I wasn't even able to actually beat the fight (and I was the older brother, so I didn't have anyone to help). But it stuck with me for years. I ended up getting a PS4, the first console I bought with my own money, for the sole reason of playing the Kingdom Hearts collections.