Your roleplay certainly fits the horror genre. The details you've added really help get someone in the mood for the story, too. Like Duke pointed out, the next best thing to introduce would be the whole point of the story (aka: the plot). What is your character going to do and why are these other characters needed? Can also point out the setting, more so to the point of the technology of the time and the location, unless neither of those is relevant to the story.

Other than that, you have a great start!

Oh, one more thing! Depending on what type of characters you want, you might want a roster. If this is more of a free-for-all, then you can simply let people know that.

Don't hesitate to ask me anything if you're ever stuck or bored. I'm usually around throughout the week. :)