My Bloody Valentine proves you can defy the tropes while still staying true to the genre.
The plot is vintage 80's slasher. Years earlier, a small Nova Scotian mining town saw a cave-in trap several miners. The men on watch were AWOL at a Valentine's Day party, forcing the lone survivor to resort to cannibalism. Following his rescue, the survivor donned his mining gear and murdered the negligent men. The town hasn't celebrated Valentine's Day since.
Flash-forward. A fresh group of young miners and their girlfriends want to have a Valentine's Day party. Unbeknownst to them, someone wearing a miner's outfit has begun offing locals. The mayor and sheriff keep the killings under wraps and cancel the party. The frustrated miners move the party to the mine. Soon, the youngsters find themselves trapped underground with the killer.
Like Friday the 13th (1980), the story revolves around a tragedy of neglect born of indulgence. In a subtle nod, the film sets Valentine's Day on a Saturday, making the preceding Friday the 13th. Like Halloween (1978) it features a holiday theme. But My Bloody Valentine eschews wooded cabins or suburban homes and substitutes a dank, dark, coal mine. It's an inspired choice that works thanks to the location photography. Another inspired choice is the script's allowance for multiple survivors. By avoiding the "final girl" trope, the film avoids the contrived plotting that goes into whittling a group, despite the natural human impulse to stick together.
Indeed, as an 80's slasher, the only things working against the film are the Nova Scotian accents. To me, they sound too cheerful and polite, giving the film an unintentional satirical tone.