Horror is a frustrating genre in that great movies can come and go in the blink of an eye. Big releases like Insidious, Sinister and The Purge open on thousands of screens and are supported by huge advertising and marketing budgets. But other more modest releases disappear after an average opening weekend. Or worse still fail to make it into theatres in the first place. So the following are a few films that you might have missed first time around; 15 horror movies that demand to be seen or deserve a second chance.