The way the event unfolds has a nice sense of surreal dream-logic, and the text--when it's not getting in the way of actual interaction, or going out-of-voice to tell you you can't (Spoiler - click to show)talk to the dog--lets you project that creepy atmosphere...but it collapses at the big reveal, changing the mood from "surreal, unsettling" to "ridiculous, eye-rolling."
It's not that the premise is bad, but it needs more setup or prose-skill or something to take it ((Spoiler - click to show)the twist) from "ridiculous" to horrific. (Just replayed "9:05" and got a reminder of how well (Spoiler - click to show)a good twist can be done.)
There's a fine line in horror sometimes, and it's a shame this one missed it, because I think there's an audience for crumb-sized IF horror.