Note: I played the initial version, or a version close to it.
I was worried about the difficulty of this game going in. The early videos usually ended in a game over, which given that the author of a game is usually pretty good at their game was a worrying sign. Skimming the comments also showed a few people found the game difficult. I did find the game too difficult, but not necessarily for the reasons I expected.
I have mixed feelings about the core gameplay loop. Mechanically, it's solid, and moving and shooting is tight and satisfying. I wasn't sure what the point of hovering was as the knives seemed to be above ground level and the ghosts seemed to take up the whole height. Carrying a girl weakens you severely, both slowing down your attack and movement, and that's something I'm still not sure about. It makes a lot of sense narratively and mechanically, but you can't outrun the ghosts while carrying or take them out quick enough to avoid being swarmed. Trying to drop the girl, defend, and then pick them up again was too complicated for me and might be pace-killing for others who can at least handle it.
There seems to be little or no bound on enemy spawning. I'd clear a room, come back, and it's full of knives again. I'd run past some ghosts, only to have them just keep spawning and end up swarmed by a dozen of them. I would have preferred more of a respite, being able to clear a room, breathe, and move on, but I think that's not going to be a universal opinion. I also would have preferred more of a difficulty ramp instead of having several enemy types thrown at me in the beginning at a pretty high rate, but again, I think that's going to be a bit divisive.
I can't comment on the boss fights as I didn't get that far. Yeah, I had that much trouble.
In other words, the game forces you to stand and fight (hey, isn't that one of the themes?) and I'm not sure if that's a good thing or a bad thing. The combat, while solid enough and not bad, wasn't enjoyable enough to make me want to engage in more of it rather than just survive and get through the level.
It really needs a map, or some sort of objective markers. It was hard to tell where I was and where I needed to go, and given how deadly the environment is, this is literally the difference between life and death. You can't really afford to explore because everything is trying to kill you.
With that out of the way, the visual design is fantastic. It's got a somewhat oldschool feel, but in a nice throwback indie game way rather than a "this is all we can manage sorry" way. The mix of normally lit environments with cel-shaded characters works great. Little touches like the animations in the dialogue and fancy main menu complete the impression.
The music is good, especially the main menu background music, but the sound design is a bit of a letdown otherwise. The dialogue skip sound is a baffling choice entirely, and the hit sound sounds like a door being slammed and there's something really weird with the positioning or stereo imaging of it. It's not horrendous by any means but it contrasts pretty sharply with the fantastic visual presentation.
I will also note that while I found the setting and premise fascinating, there's a lot that went over my head. In particular I have no idea why Song is throwing cards as an attack. To my entirely Western educated mind that seemed a complete non-sequitur.
Finally, I'll try my best to answer the specific questions you're looking for feedback on.
How do you feel about the 3d movement/shooting mechanic?
See my comments above. It's solid and well-implemented, but doesn't stand out on its own.
EDIT: After reading some other comments I realized this question refers to something completely different which I never really experienced ingame.
If you have to play procedurally generated chapters repeatly, do you feel if it's repeative?
I didn't actually realize this game was procedurally generated at first. I think it's fine but will eventually wear out its welcome.
If it's a local multiplayer game, do you think it's better to keep in one view and it should split to multiple view?
I think it would have to be multiple views. One view would be better for this type of game, but unless players are locked into a room or limited by some sort of tether they can separate across the map. That means zooming out really far to keep them both in view, which means they'll be almost impossible to see given the size of the maps.
What elements do you want to add in the game?
I could list a lot of things, but I think in the end I want a very different game from the original vision. In general I'd like it to be more forgiving, but I'm not sure if that's the right direction to take this game.
Overall I think this is pretty good game with a few minor flaws, mostly to do with the audio. I think the gameplay is going to be divisive, though, and it just wasn't to my tastes.