Oh dear. (spoilers)

I had a tough time making it through the awkward dialogue in the very beginning. I turned it off at:

"Get enough sleep?"
"... Rough night."
"Nightmares back again?"
"... They never left."

Come ON. Trying wayyy too hard to make the character a stoic lone wolf badass type.

(spoilers)

The acting/dialogue does get a bit better as the movie goes on and admittedly, the initial setup of the basement security thing with the gate is interesting. But, it turns out to not really make any sense. Several things don't make sense actually:

The gate itself (keeps dead/evil spirits inside) doesn't make any sense. Let's ignore the notion that we could just fill in the entire basement with concrete and seal them off forever. The movie has to happen, right? So we'll ignore that one.

But if we need to keep it closed to keep the evil spirits inside, then why ever open it, ever? You saw footprints on the camera? You saw a shadow go by? Okay... who cares? Why even open it and risk letting them out? Isn't that what the monsters want? For someone to open the gate... so they can escape? If the gate doesn't actually keep them in then what's the point of it at all..? Again, I know that a movie needs to occur. If no one ever went in the gate, the movie would never happen. But there's gotta be a better justification for going in there than, "We saw some slight evidence that there are monsters in there. So, therefore, let's unlock the gate and go inside and look around in the dark for them." WTF???

The ancient man in the penthouse isn't really explained and seems to be taken from vampire movies. The impossibly old, bedridden yet undying powerful leader guy...thing. I swear that was in Underworld or some similar vampire movie. Him being some kind of mystical guardian, so long as he is living, is also not explained.

The movie can't decide whether the monsters are zombies (physical beings that are restricted by physical things like walls and gates, and who attack with their hands and mouths), or spirits, that can simply materialize anywhere they want willy-nilly (looking out menacingly from the windows, for example, when nobody was really in that room), orrrrrrrr manifest in the dreams of living people. Apparently they are... all types.

The movie doesn't explain if the main character was asleep, or unconscious, or possessed for the five days he missed? Also: Why. The movie SEEMED like it was implying that he was possessed for that time, and it SEEMED that it was going to reveal "Oh crap! I murdered somebody during those five days! Oh no!" or something like that, but instead it just never explained it at all. He lost several days and... we never talk about it again and never figure out why.

The movie didn't explain the significance of the clock always being at 3:00 (did I miss it?)

It didn't explain who took the old guy security guard's eyesight. He just said "they" took it. Who? The ghost-zombies? Or the two owner guys? The CIA guys? Also: Why. I don't think it was the ghost-zombies because those things just attack by grabbing at you and pulling you into darkness and eating you or whatever. Can't imagine zombies deliberately aiming for their target's eyes. But why would any of the other characters in the movie intentionally blind their own guard, when they clearly need his expertise? I kinda think they just wanted the "wise blind man" trope because they thought it was cool.

It also didn't explain the CIA presence. If the CIA controls the whole thing (and that was supposed to be some kind of twist I guess), then why not just have the CIA guard this gate to hell with military presence/equipment? Why gamble that some random-ass Joe Schlub security guard HOPEFULLY doesn't open the gate to the goddamn netherworld?

I dunno. As I said, the initial setup with the security room and the gate was, admittedly, unique. The actors did an alright job, aside from some lines, especially the very beginning, being super cringey, but the plot itself, and most plot elements, were nonsensical.