There are a lot of smaller details I love in this, but the primary weakness is how hazy and sort of messy it feels as a whole, in turn making the VN a difficult one to talk about. Let me try my best to unpack all the ways in which I think the core conceit hangs and fails to hang together:
Unless I'm missing a more specific reference, I think the folklore being riffed on here is all the "stay in this scary house till sunrise [for whatever reason]" stuff, and as that kind of story it's pretty weird. The vibes in the beginning are that all the characters are sort of participating as a bit or as an excuse to hang out, not really expecting anything supernatural to happen; and indeed, nobody (with the possible exception of Rai?) seems to care about their wish by the end. There's a thematic thread about childhood and childishness, but I don't think it really materializes with how skeptical everyone already is by the start. In this sense, the actual plot is all character drama, and the spooky folklore mostly amounts to backstory the characters sometimes think about in parallel to their own lives.
I'd be fine with this otherwise, but ultimately, I feel like it might be too much of a deflatory move to initially tease a supernatural direction and then instead deliver something much drier and more subdued. The scene with the wolfies really underlines this, I think: it's a pretty neat horror moment – though I don't know if I can buy that Federico only noticed them at that point – but why is a horror moment happening this late in a story that has otherwise done little to build up an atmosphere of suspense or dread? Then, on the other hand, given the decidedly grounded tone and the characters having little faith in the supernatural, Fede's idea to come out not-quite-kinda-sort-of coinciding with a sincere attempt to make things go well with the power of the wish might defy belief. (Also, ding ding CinemaSins: if the wish is granted at the end of the night, why is he having the talk before?) I think there's maybe a missing piece of characterization to really explain why he has decided to carry out this somewhat convoluted plan in this precise way – maybe I missed something, but for instance, I don't recall if Rai's presence was something Fede outright wanted or if he was just needed to access the wish mansion. Like I said, it's all a bit too hazy.
On the other hand, the character drama is by itself mostly pretty good. The plot sort of functions as a social issues particle accelerator in that there are a lot of clearly identifiable topics in play – coming out as bi to your straight partner, awkwardness with friends you've banged, relationships between gay and not-gay men – but it all works because having so much going on at the same time cancels out the risk of feeling like just a lesson about a particular theme. How the story navigates its overlapping threads grants it a lot of dynamism and intrigue, since it's not immediately obvious what the conclusion is going to be.
If there's a short end of the stick, I think it's Anna's part; I didn't check, so this is just a guess, but it feels like we're in her head a lot less overall, and her perspective doesn't always add a lot to the scene. It's a bit of a shame that her epiphany is so internal in contrast to Fede and Rai getting to talk with each other about their feelings, and it's strange that the story teases Anna and Rai forming a relationship but doesn't show a lot of them hanging out.
Another good element is the sense of place (with a couple of asterisks). Having photos of a specific real building that all fit together cohesively is a big boon for the VN, and in fact some of the stock images come off as jarring in comparison because of their "professionally bland" aesthetic. There's maybe an argument for going all the way and getting the rest of the images yourself, or at least choosing CC stuff that isn't overtly stock photo-esque. (See, for example, the Instagram-ready shallow depth-of-field in the car BG).
This is just nitpicking, to be fair; I think there's a bigger issue in how brutal the day for night is for many of the interior images. It's beyond simple photo editing to make daytime shots featuring lots of windows and inside light sources look convincingly nightly, and the filters aren't heavy enough to really help. When the premise was revealed, I was half expecting a backstory where Loudo & co actually sneaked in to take good night photos... but I guess nobody went to prison for this maywolf. Anyway, it's kind of brutal how the prose specifically points out that everyone is using flashlights but then most of the photos don't look at all congruent with that. The art and the character designs I do like, and it's especially neat that Anna's color scheme is so carefully coordinated but the boys just kind of wear whatever.
Ultimately, I don't think this is the best work of either co-author, though obviously the bar is set pretty high by what both have released previously. I don't want to get too symptomatic, but given the VN was pitched as a co-writing experiment, I can't help but feel like a lot of what doesn't work is consistent with the overall vision maybe not being quite clear enough. There's a lot of back-and-forth and a sense that the writing isn't always super confident about laying down facts and making decisions. How far into the horror elements do we lean? What kind of mood or ambience is there? Do the characters and the story take the wish thing at all seriously, and what's everyone's precise motivation for being here? How melodramatic does it get once everyone starts arguing? The pacing of individual plot beats and reveals, too, feels a little muddled.
I know next to nothing about the actual writing process, of course, so take this with a grain of salt. It just feels noticeable to me that many of the story's best details involve the house as a physical space – see: the wolves, or all the exhibitions, or just the tangible sense of how the characters move around it like when Fede thinks about wanting to step 2 stairs at a time – but there are a lot of stumbles in how the actual plot plays out. It's a VN that works better when it has something concrete to lean on, and it feels like the story often comes short of providing that.