I'm not familiar with Silent Hill so it makes perfect sense that I didn't get it. There's always going to be someone left out when it comes to a specific reference and that's okay. I assume you took some inspiration from it to make the game so it seems appropriate.
I think it would've been cool if the secret revealed something about the backstory perhaps. Could be about the monster lurking outside or the identities of the other victims, something like that. Just some ideas, hope that helps.