CrazyIvan777:
My original reasoning for this was to let the PC's know that one of the 'wrong' things in the diner is that the tile isn't the same as the original diner. But the PC's are sure it's something other than this, and they're so insistent that I kinda -want- it to be more than that now.
This is the key to the whole thing and it's a golden gift to you: something your players are bought into as interesting, without you having to have done much to
make it interesting. Given the shattered ruins across the landscape of this hobby of things GMs invented to be interesting which the players subsequently yawned at, this is a thing of beauty.
So, decide: it
is more now than you thought it was. Take whatever you had in mind and set it aside. You can bring it back later in part or in whole, if you need it.
Basically, your next step is to mine the players for their ideas. You know how when a TV show does something mysterious and the fans come up with tons of theories as to the meaning and often those theories are better than what actually comes about, and sometimes the show runners will actually use ideas that are popular with the fan base? Tap into your players for this. Ask them what they think is back there. Ask them what will happen when they take it off, or even just try to. Set the game aside and talk about it like it's a show and you're all fans of it. Build it as big as you want, then and there.
Then pick the game back up and play that.
You might be saying "but then there's no mystery." Right, not for the players, not any more. They solved in in the jam session you just had and it was fun and exciting and people were probably saying things that startled themselves as much as anyone else.
Now the characters get to go through what you came up with, or some version of it. The character don't see everything, don't understand everything, don't know about the scene you imagined between two NPCs that they haven't even met or heard about yet. But they'll see the residue of those things and all of you can thrill to the idea of how the characters will react in due time when they find the
next thing that is significant to all of you, but baffling to them.
I sort of roughed all that out, above. What it comes down to is asking them, at least a little. If they say "There's a message there" then guess what: They don't think having a message there is too cliche. They
expect a message there, and to some degree
want a message to be there. Maybe they don't come up with what the message says, maybe that's up to you, heck maybe the "audience" doesn't even get to see it yet. I'm pretty sure I've seen shows where all the characters knew was some message was, but none of the actors or viewers (or even the showrunners, think "Battlestar Galactica") did. It works.
I love discussing this, so feel free to ask what my babble is about.