Going to Hollow Bastion for the first time in Kingdom Hearts. The fact that it's not a lighthearted Disney world, but the lair of the villain you've been pursuing across the cosmos should have been the first hint that shit was about to get real.
I remember feeling confident that I could take on whatever the world threw at me. I'd just finished up Hercules Cup at Olympus Coliseum and scored the tremendously cool Metal Chocobo keyblade. Nothing could challenge me, I had the touch, I had the power.
And then Riku shows up, asserts his utter dominance over you by forcing the Keyblade to choose him instead of you, and leaves you to face Hollow Bastion with the same toy sword you started the game with. Of course, The Beast does most of the heavy lifting until you finally get the Keyblade back, but the moment is still pretty heavy. It was like the game was saying, "Oh yeah, your intentions are good and everything, but Riku is still stronger, so he wins. Doesn't really matter that he's on the wrong side, he's still tougher than you, so that's the end of it. So sorry." Definitely an OMG moment.
