Musebox!

This late at night, the shop normally only sees a few stragglers. People coming back from late work shifts, rowdy teenagers roaming the streets, people like that. Right now, there's not a soul in the place aside from the busy workers.

Firo’s wiping up the counter while the proprietors are in the back, sweeping the kitchen and cleaning out the oven. Tidying up is the last thing before they all head up to bed in the apartment above the shop. Firo's dreaming of his bed right now, something that he still hasn't learned to take for granted in the years he's lived here. There's never been the slightest hint of talk at throwing him back out on the street--and he's certainly kept his ears ready to hear it--which is puzzling to him. Puzzling and yet... it makes him very happy too.
 

The bell above the door jingles, and Firo holds back a growl of annoyance. Even after a few years working at the pizzeria, his ‘greeting skills’ can still use work. He doesn’t yet look up from scrubbing at a particularly tenacious stain as he welcomes the person, “We’re closed. You want something, you come back at—“

He cuts himself off when he finally looks up to see their would-be-customer.


...Or not. Firo, at first, sees no one. It's not until he leans farther over the counter that he manages to spot the tiny figure that's just come into the shop.  

"Who're you?"

Location
1. Mine shaft: Chances are, this place was abandoned for a reason. 
2. Home alone: Haunted or not, home's suddenly seeming a bit less sweet. The lack of background noise from other people means you're free to focus on all those spooky creaks and groans that houses make. To make matters less comfortable, the power's winked out too. 
3. School: This place has seen better days--many of those cute, educational posters have been torn off the walls (or warped into something else), desks are tossed around, etc. 
4. Sewer: The stench is probably the least of your concerns. Not only is this place pitch black, but the walls and the weight of the ground above make it more than a little claustrophobia-inducing.
5. Professor Layton’s torture chamber Saw-style dungeon: There’s only so much time for you to act before the guillotine blade comes down, the chamber fills with water, the electrical circuit turns on, etc. to end one of you. The un-trapped and the trapped may need to work together to save the day! And quickly. For an added twist… Are you both trapped? That’d be a real pity if only one could be saved.
6. Gothic castle: Thunder and lightning are probably crashing in the distance. The furnishings in this place may look plush and extravagant, but it's hardly a comfortable place when it's this eerie. 
7. Hospital: What's scarier than tons and tons of germs? Whatever's lurking in here. 
8. Hotel: Do I even need to quote the Eagles here? Whether you’ve been locked in by a creepy bellhop, an elevator that just doesn’t take you where you need to go, or you’re simply snowed in, the cabin fever must be getting to you.
9. Arcade/pizza place: You know the drill. In the dimness, even the most cheerily grinning of children’s mascots look creepy. Especially the most cheerily grinning.
10. Library: The looming shelves may provide cover, but they also reduce your visibility. And don't look too hard at the shelves, or else you might see some really creepy things. 
11. Prison: Escape from this place is probably going to be even harder than from any of the other locations. The random clanging of bars just adds nicely to the atmosphere. 
12. Circus/carnival/creepy puppet show: Who left all this junk out here? The rides and attractions have definitely seen better, less rusty (or is some of that blood..?) days. Of course, they might still pop back on occasionally to startle you. 
13. Just a straight-up weird hallway: No matter which way you walk, it never seems to end. There may be more snags as well--for example, is the trash strewn on the ground actually composed of oddly personal objects from memories you'd rather forget?
14. Remote cabin: Home, but with a twist. This isn't as familiar as your own turf and anyone who could help you isn't around for miles. 
15. Wildcard: Mix and match or make your own!

Threat
1. Bump in the night: What’s that sound? You know, that low creak or sharp rattling. Whatever it is, it’s coming closer.
2. Ring ring!: Someone's calling you and they're probably not a friend. 
3. The prowler: Either you already know the monster is out there or you’ll find out soon enough. While it may even look human in appearance, this thing can’t be reasoned with and has only one thing on its mind: hunting you down.
4. Man is the monster: Murderer, stalker, whatever. There’s another human (or close enough) out there and they’re not friendly.
5. Rube Goldberg’s baby: Traps, traps, and increasingly convoluted traps. Essentially, more Saw stuff!
6. From beyond: Maybe it's a seance gone wrong or the place has always been haunted, but now there's a ghost on your tail. Are you helpless before it, or can you take this thing down Ghostbusters-style?
7. And it's not just the fog, either: Freaky weather that may or may not be supernatural.
8. …You!: One of you is secretly the murderer/stalker/monster. Does the other find out in time? Is the unmasking startling, emotional, or more Scooby Doo-style?
9. Budgeting: Light sources, barricade materials, whatever, you only have so much of that very, very necessary resource. Can you last?
10. The second variety: Robot, animatronic, etc. It's just doing what it's programmed to do. 

For added fun, you can pick which essential horror items (flashlight, board with a nail in it, camcorder, mysterious key, chainsaw, static-y radio…) the adventurers have and which they have to do without.

Thanks to Lanie and Rev for ideas and moral support