I would consider Abattoir to represent the genre of speculative horror. The plot centers around a mystery that is never completely revealed although frequently alluded to.
It has an original mythology of its own, even though it heavily relies on tropes of the past, combining some of the more prevalent ones, like Satanism or ghosts hauntings into a single coherent whole.
The movie seems to be aiming for a sequel, because the story remains somewhat unfinished, but not in any annoying manner, which characterizes some modern movies.
I liked the fact that the plot was relatively easy to follow, that the visual aspects were displayed but not to the extent of overshadowing the content.
I really, really liked the villain. Naturally, not as the person I would want to hang out with in a coffee shop. But he was every bit as striking as the antagonist of the horror classic, the Cabinet of Dr Caligari. Horrifying with his appearance, intentions and motivation, not to mention his unusual powers.
For reference, I would loosely classify Abattoir, Death Note and the Ring as all belonging to speculative horror, even if the craftsmanship, and the consistency, vary from one to another.