Is there any sort of plot in this one? Did I not notice it while skipping copious amounts of minor personal exposition? The only thing that stood out was some twins(?) digging into MC's past and him getting a phone call about.
I have to disagree with this idea. This VN has a wealth of well-established character motivations and a very strong narrative thrust. The MC is trying to rebuild his entire life and regain his basic purpose for living after losing the love of his life (Zaina), which was a tragic and vivid event that shattered all his hopes and dreams of spending the rest of his existence with her. Plus he is having to overcome mental health issues from being a war veteran. The player has the choice of focusing on pursuing a single love interest to fill the void left in his heart, or they can lean into the playboy nature of the character to some extent (these choices align somewhat with the fame or infamy routes the game offers).
The love interests themselves are dynamic and fascinating characters as well. Els is similarly dealing with mental health issues as a war veteran, and she has unrealized dreams and unmet potential due to her family situation. Kana has physical health problems combined with a haunting memory of personal betrayal, and she is trying to come to terms with her past. Amrit is pursuing a lofty goal of becoming a champion under the tutelage of the MC and McNab, while learning to grow into a sexually active and confident woman. Vi is lost and directionless in many ways, since she is relatively young and tragically lacks a family to support her, and she is just beginning the daunting process of choosing a life for herself. Ines is hiding deep insecurities about herself behind a constant public illusion of sexual bravado, and she has to decide the person she wants to become.
Even McNab is compelling in his struggle to overcome a serious injury and regain his past glory in the MMA world. The most important part of all this though is that the MC is involved in each of the conflicts of those close to him, in very real and interesting ways (he is training Amrit and Kana, giving Vi and Ines a place to live, working closely with Els at the veteran's shelter, etc).
Yes, there is no clear and decisive external struggle that has been fully realized yet in the story, but there are hints of important ones to come in the ex-convict MMA fighter who is targeting the MC, and the unresolved matters of Davis' supposed death and Zaina's passing and the secrets that are being kept there. A lot of things have been set up – like the hidden injuries that can be accumulated by the MC during his fights, or injuries given to Kana when training/competing with her, depending on player choices over the course of the game – that will likely impact the events that will unfold in future chapters.
So yeah. I strongly disagree with this idea that the story lacks a plot or a compelling narrative.
STWA: Unbroken is filled to the brim with motivated and interesting characters, and this wall of text I just wrote is only the bullet point version of the incredible depth of story that's actually offered in the VN.