Resident Evil: Silent Hill would never work. Silent Hill is a manifestation of your inner horrors, not even perceptible by some. You're not killing zombies in the game. In fact, there are no Zombies. It's survival horror, not a shooter. Nobody in Resident Evil would have any reason to be there. It's a personal experience, not a super-natural infested town that needs to get "taken care of". It's more personal than that.
Dat passion. I agree, these are not really games that could realistically overlap.
Silent Hill 2 is a game I did a lot of research on when I wrote my Junior research paper back in high school. The topic was why video games are the best medium for the horror genre. I played through it 3-4 times while I was doing it.
I wish my high school was that cool, when i was in school bringing up video games in class was almost taboo. I heard marvelous stories of some teachers actually encouraging that kind of talk but i never had any of their classes. Le sigh.
I don't mean to ramble, but people who talk about Silent Hill without knowing anything about it really bothers me. It's not the same if you've looked it up on wikipedia or if you've watched a Let's Play of somebody else experiencing something designed to put fear into the person experiencing it. It's one thing to love a game for what it is. Silent Hill 2 is certainly not a game without flaw, but it seems to me that there's a group of people (not saying any names, because this doesn't really even apply to what SeaOfWhispers said) who've created a fandom dedicated to the doings of a fan of a video game, movie, book, and not actually being a fan of that video game, movie, etc..
There was a girl I knew in high school who happened to like Resident Evil an awful lot. A disturbing amount. Like suffocate yourself in a sandbox because you liked Naruto disturbing amount. She'd play a game, download skins for her favorite characters, but the way she would talk about it didn't really seem as though she liked the game all that much. It almost seemed like she was playing it for the sake of being a fan, for obsessing for the sake of obsessing, not because she actually enjoyed playing the game.
It just pains me when I hear somebody refer to Slenderman as Slender, or when somebody talks about Pyramid Head like he's some scary monster that haunts your dreams and will kill you. No, he's not. He won't kill you. He's not after you. He's after James Sunderland because
he's a manifestation of Jame's regret of having mercy-killed his dying wife and the lust and anger he felt when he couldn't do certain things with her, implied by a certain scene early on with a very long sword used in a particular such a way on an oddly feminine zombie./rant
edit: Oh, and Legacy of Kain 6.