It's weird, because it's completely different from the earlier demos in terms of content. Both characters included and routes included. Looks like the game's undergone a full rewrite as well as a full art redesign.
As you mentioned, if it's now a unity thing that means it's changed from being a Ren'py thing. People were actually doing sprite swaps earlier in the thread. Basically literally everything that they did up to a certain point has been dumped - story, art, engine, everything.
Let's be blunt; at this point nothing remains of the original premise. this is not a large cast of writers and artists, and chances are basically all the larger team's work has either been thrown out or never materialised in the first place.
Great little example of this:
Doing this also made me realise that the old title card background is the background of the new title card background. also this all reminds me of steven universe, and i don't really see that as a good thing because there's no thematic reason why a game trying to be mature about relationships yet makes people as wet as Lake Disappointment would be associated with a show about a fat kid hogging the camera in an interstellar war drama.
Cutting back the team so much is realistically the only way this game is going to get finished, a small, focused dev team, but with such a complete reset the damage has already been done. I'm guessing basically nothing remains of the work done before a certain point, especially with some of the existing matchups already seemingly being rewritten.
If there's one of these title cards for every chapter, it's eventually going to become obvious that most of the writers are just gone. Someone (possibly a Kiwi) is gonna ask, and it's gonna start alllllll unraveling.
But I've finally, finally figured out the parallel.
Ultimately, what we have here is less a full-fledged dating sim with a fun cast of characters and more like... wait for it...
A Fire Emblem game reduced to JUST the support conversations. No tactical gameplay to beat up baddies while fostering possible relationships, no cool animations, no little happily ever afters, no overarching story, no fucking your best friend's time-travelling daughter so your child can wield the boxart sword, just the pure fuckin' few-paragraphs-long support conversations.