Extremely creepy! I love the mechanic of summoning the candy, too.
Nice variety in the trick-or-treaters, although it's a little unusual that they have such specific demands.
I fumbled somewhat with the mouse controls--I'm not sure exactly what the problem was, but I often had a lot of trouble interacting with the piece of candy I needed.
Also, there should be more direct feedback when I have successfully satisfied a customer. (I know, he disappears, but I wasn't sure if he might still be there in the room with me--he should have said something.)