OK, I played the game and I can offer some feedback.
First of all, I quite liked the experience. It was short, well done, silly and smooth.
Not particularly funny, I'm afraid: I hoped for more humour, but I think everyone has their tastes in that kind of stuff, so no big deal.
In its current state, I'd rate it 3,5 stars, but It could easily aim for 4.
I personally do not like HS renders in general, so I won't comment on that, as it's a personal preference and I wouldn't be objective.
My main gripe is with the omnipresent, neverending "..."s
Personally, my feeling is that trick is way overdone, and you really should consider either adding some text/dialogue in your "action" scenes, or shortening them.
And just hide the chatbox if nobody is going to talk.
So far, the first episode is just left there, hanging. I suppose you want to bring back those characters in a way that links the two investigations together and shows that they are connected, honouring an ancient tradition in the detective mystery genre, but so far it just drops out of the narration falling nowhere.
I think you should have that thread pop up every now and then: like showing Nick investigating the club at the start of an episode before turning his attention to the main topic (a bit like a Bond Cold Open), or him receiving a brief call from Bill asking how the investigations go, or having the black bull loom from a corner... that kind of cheap trick.
Technically, nothing to report. There's not much that can go wrong with a linear RenPy kinetic novel.
I'd like it if you considered differentiating speaker names by colour.
I'm pretty sure that some of the times where Nick speaks in the first episode are actually Bill's lines. Also, there's an instance (during the sex scene with the fat receptionist) where I couldn't tell whether the one speaking was Nick as narrator or Nick as character.
The hardboiled language is there, even if without the "Private eye monologue" that one would expect from a game with the name Marlowe in it. There are a few lines that sound weird to me, but I'm not a native speaker, either, so it could be me.
You know a detective is a true badass when his cat is more badass than him.
I hope the sex is intentionally built to be as unerotic as possible, to emphasize the moral degeneration of the setting, because this could be the least arousing game I ever played since Call of Duty 2.
I'm not one of those players that need animations so that one isn't the problem, but the style of camera shots taken from different angles is too drawn out. The idea is workable, I think it just needs to be quicker and more varied, with more different poses. For example, the shotgun scene: once you see the whole barrel, there's no need to further zoom in.
The episode "videodrome" is way too short and incomplete and IMHO it can't stand on its own legs. Nice trick with the pixel noise, tho.
I agree that the harem tag (that has gone from the Genre section in OP but it's still in the thread description, I don't know if that's under the power of the dev to modify) should be removed, as there's nothing of the sort to be found in the game.
So far Nick has sex with, let me count... the grand total of 2 chicks (BJ from Vicky in the first episode and the fat receptionist), so I wouldn't call it a fuckfest, either.
Noting much in the Romance department so far, maybe Nick will develop a relationship with Jessie in future, but tags should reflect current content.
And... you can't have a hardboiled Private Eye called Marlowe and not have him learn important plot points by hiding in a room and overhearing the villain talk! This is abhorrent to me!