Hm. Everyone is saying the Mass Effect games it seems. I've still never played any of them.
Anyway, probably Kingdom Hearts. I mean, replaying it on the HD re release was nice and all, like revisiting an old friend, but it pales in comparison to how the game felt my first time playing it. So much wonder, so make joy, and it was the first video game ending to make me tear up a bit. I mean, the ending still tugs a bit at my heart, but I don't cry over it...sometimes.
Speaking of which, do I ever miss gaming when I was younger. I mean, sure, today having much more access to video games is nice and all, and I can finally keep up with all the latest, but when I was younger, I relied strictly on my parents generosity, which was severely limited to birthdays and Christmas if I was lucky. Every new game felt great to get, and I'd do my best to make it last. Each one was like literally exploring a whole new world.
Today I just plop at my computer desk, say "What game do I want to play today?" and then continue to play it anywhere from 1-3 days (depending on the length of the game) and beat it, only to move on. This is all assuming I didn't get bored of the game before I got that far, or other more important things didn't get in the way.