Like the geek I am, I'm organising a gaming marathon for my 18th birthday party, so I'm looking for a good scenario from Call of Cthulhu to traumatise some of my innocent friends with. The player group will be a mix of noobs and vets, and I was looking for something particularly interesting/terrifying that the GM can work with. We (the experienced players) have already played the entire Stanton Street set (plus the loosely related spin offs in the Dreamlands), The Dreaming Stone, The Eye of Wicked Sight and quite a few of the short, one play session ones from www.shoggoth.net and yog-sothoth.com
So, does anyone have any suggestions? Any scenarios they particularly loved?