I kind of hear a "Halloween" piece within this. But, as for a horror soundtrack I just don't hear it.
There's a chord of which I can not name. But, lets say you play a G note on the 6th string (3rd fret), you'd play it with the C#/Db note on the 5th string (4th fret). Whatever that's called, it's popular in horror film music. It gives a morose feeling to the music. Also minors and lots of flats. Your's just sounds too happy and steady.
Well, I tried matching it up on youtube with a few stalking scenes from horror movies. First, I think this is more of a songwriting thing, not a mixing thing. Just to be fair.
The biggest issue I had with it was the tempo and preciseness of it all. I shouldn't be able to nod my head accordingly in time with eerie suspenseful music. It should be jagged and...suspenseful. Not predictable and bouncy. The instruments are just fine, good choices actually. It's the way they're played and the impression they're giving in relation to what the notes and chords make you feel. I would be interested to hear how it works with the timing stretched out... slowed down and played over again so not to be in perfect pop tune timing.
That's a tri-tone, and there are several in there, as well as flats.
intro or a stalking scene. Kill scene would be way more staccato and dissonant.
I listened again and I still don't hear it. I don't even hear the tri-tone (thanks for that info. The next time I want to describe those notes I'll have to search out this thread. I can't remember a damn thing anymore)
Intro, it's good as is.
Stalking scene, IMO not quite there.
But, most important, did they send you the edited scene? If this is just going to be dropped in the background, then it's fairly good to go. If they want to lay this into a scene to use as an essential part of the scene, you should do that with a final edited scene. It doesn't need proper sound or color correction. But, you need to see the scene to write the music for it.
... it's way too much of a "song" and not ambient enough.