This VN looks promising so far and I look forward to seeing where it goes. The artstyle is great, the nightmare sequence had some excellent writing and the soundtrack and SFX were effective. Just a few criticisms:
Adding sprite expressions should be a priority as the mismatch between the group/character's mood and some of the sprites broke my immersion quite often. If the initial sprites were more neutral in expression this probably wouldn't be as big of an issue, but seeing Mason's goofy grin during a depressing or tense scene is rather off-putting. I can see in the Dev Log that you're already planning to do this and I'd urge you to add them in for the next build because this is probably the most obvious issue right now.
I also had problems with the ending of the nightmare sequence where Zeke meets the Stranger, which is a shame because up until that point I was enjoying the writing. I found it to be rather anti-climactic and instead of enhancing the tension built up to that point it just ended up deflating it prematurely instead. I think the main reason for that was the inconsistencies in the Stranger's characterisation and the dialogue being too lengthy due to unnecessary explanation. The Stranger sounds formal and old-fashioned sometimes but occasionally they speak colloquially and the contrast is jarring. This detracts from the refined yet sinister aura that seems to have been intended. It doesn't help that Zeke's reaction to being manhandled is almost nonexistent. If he had a more pronounced fear response and showed more signs of hesitancy that would have helped portray the Stranger as something to be feared. Alternatively, having some of Zeke's internal narration about how he feels would help achieve the same purpose. Then there's the (over)explanation the Stranger gives in this scene. I don't think they need to be explaining Zeke's dream and it's mechanics, that just lowers the tension of the scene and clashes with the their previous cryptic attitude during the phone call. (As an aside, people don't actually have one long stretch of REM sleep, instead they typically cycle between REM and non-REM). I think it would be better if the Stranger got straight to the point, preferably speaking in a way that matches our first impression of them. Of course, if you deliberately want to present the Stranger differently in this scene then that's your decision but you need to find some way to address the mismatch between the reader's expectations (considering the buildup of tension and dread up to this point) and the new impression you want them to have. Otherwise the scene will be an anti-climax and break the reader's immersion. If I were you I'd completely rewrite this scene after carefully considering the impact I want to have on the reader and how I want to present the Stranger. It's the only instance in the VN where I felt the writing was notably substandard.
Finally, I felt the dialogue could be stronger if the characters' voices were differentiated better. I'd expect a diverse group of characters to have some differences in accent, vocabulary and style of speech but most of the dialogue felt too generic. I wouldn't be able to tell which character was speaking if it wasn't for context and the character tag and that's unfortunate because a unique voice helps characters feel fleshed-out and realistic.