I'm not sure you understood my previous comment. I didn't mean that you can only read it and do nothing. Also, it seems like you've only played the first chapter; the game currently has seven.
To answer your point: It is a game. It's a visual novel with mini-games and a dating sim — your choices determine who you date and what ending you get with them. You also change a lot of what happens in the subplots. Only the main story is fixed, and that's true for a lot of games, especially the big ones.
Just so you know, this is a huge project — over 100 hours of content is planned — and our small team is working really hard to make a deep, interesting world. Adding alternate endings for the main plot just won't work for this story. Regardless, each player will still have a unique gameplay experience.
By the way, the term "visual novel" refers only to its format — a long, story-driven experience with visuals and music. It doesn't automatically make a game choice-based. Some are highly interactive with choices that change the story, placing them in a sub-genre like "interactive fiction" or "choice-based adventure." Some are not. We're somewhere in the middle.