I've played plenty of games where I got a base level caveman satisfaction for beating a really hard boss or hard level, but I think Silent Hill 2 is the first game where I felt EMOTIONALLY satisfied at the end. As I continued to play through the game and finally discovered the secret to Silent Hill, my mind was truly blown in a way almost no media had before, never mind a video game. And just by pure luck I got the "Leave" ending (IMO the best) and I seriously sat there bawling as it played.
And like Yahtzee, I was extremely disappointed that the later games didn't follow this up.
And like Yahtzee, I was extremely disappointed that the later games didn't follow this up.