FACT’s “Greatest Horror Soundtracks” playlist is long, exhaustive, and at times unremittingly dark. But it also works — really, really well. There’s a core reason for its success: Instead of overwhelming listeners with a back-to-back onslaught of classic terror moments (see Bernard Herrmann’s staccato stabs in Psycho), they employ a DJ’s sense of pacing. Thus, those peak terror moments burst forth from stretches of smoldering dread and droning unease. Another standout quality is the sheer breadth of the composers spotlighted. All the giants we know and love are included, from John Carpenter to Goblin to Krzysztof Komeda. But FACT also includes many newer works, like Mica Levi’s unnerving music for director Jonathan Glazer’s Under the Skin and the Climax Golden Twins’ creeping transmissions in 2001’s Session 9, an underrated gem of psychological horror.