It's their formula and Headpat is of the kind of 'don't shake the boat when it somewhat work' when... there was an interest to actually shake the boat with this story when there were early attempts to give the MC a chance to fight it off. The previous game allowed the MC to actually do something. Not much, but it was still something that could have led to him being the father of Sana's kid. In this game? Beyond an early prompt involving Raze which so happens to 'always fail', you can't avoid it. Same for the Spider Boss. You are meant to fail it since, for some odd reasons, you can't still level up.
Early on in the thread I called this a mix of Sana and their first game, and that was something of a disservice. Because this game is the worst aspects of both. I am not even mad if it had been presented as a NTR-only game, but they have made it clear early on this game would have offered two paths to follow, and yet they backtracked the moment their backers got fussy they didn't get their ideal NTR-only game.
If only some creators could be a bit more honest rather than throw half of their initial fanbase under the bus.
As I understand it, Headpat still plans to add a non-NTR route, but is focusing on the NTR content for now, the same as they did with Sana, no? If I remember correctly, the non-NTR route didn't have an ending (or even any sex content) for the vast majority of that game's development. If I had to guess, dev is probably locking off the non-NTR route until there's actually something there, as opposed to releasing a couple dozen builds that just have nothing on the non-NTR route.
Luna's just a pretty standard tsundere, it just so happens that when you mix a tsundere character with an NTR plot, the mixed signals from the tsundere architype just get even more mixed and it can get confusing and contradictory fast, especially when the tsundere character is also biologically primed to get stupid horny stupid easy. That's just one of the risks that comes with anything where you're writing characters, not everyone is going to like them, and even fewer will like the specific mix of characters and situations.
And *of course* the game is going to be rough and unfinished feeling, potentially even "the worst aspects of both (Sana and their first game)", the game is still very much a work in progress. Dev hasn't even finished the first town or really started on the second, and people are out here reviewing it like it's a finished product. People were pissed about progress on Sana too, and now I see a lot of people saying it's his best game, and some even calling it one of the best NTR games out there.
Long tl;dr, give it time. Game is still *very much* a work in progress, and the dev has been adamant that as development continues, many of the complaints people have will be addressed, particularly with regards to pacing and the later addition of a non-NTR route. If you don't like the game in it's current state, try giving it a solid few updates before coming back. If you don't like the mix of tsundere + NTR, then I really don't know what to tell you, that's just a preference thing. For an early active development game, it seems just fine to me.
Short tl;dr, the game is still very early in development. Give it more time, come back once things are more finalized and polished, and you may have some of your opinions changed. Or don't, I'm not your boss.