Whoah. Not such a dumb question after all! I think I now know how to get into the spooky grounds in such a way that I can get back again. If I'm correct, this is a very clever puzzle, indeed.
On my first trip through the game, I had no mask and ended up with the vampire with the sweet tooth. On my second trip through the game, I used the voodoo mask and ended up with the werewolf and subsequently got killed. Am I right to assume that the room (and monster) you access from the plain well-lit room depends on which mask you wore when you approached the mirror in the darkened room? If so, that means I've got five scenarios to work through - one for each of the masks and one for no mask.
Strewth. This is one big game!