8 Days with the Diva is a choice-based VN about corrupting D.Va with a lot of brainwashing and a lot of sex.
The game has a fairly weird tone about it. On the one hand, it's got quite the dark subject matter. It's all about mind control and corruption. On the other, it pushes hard enough into humor and absurdity to take a lot of the edge off. I feel like this approach might piss off people who would prefer either more darkness or more humor, but it is what it is.
The story of the game is naturally centered around 8 days of brainwashing D.va. Depending on what mind control tasks you have her perform each day, D.va will be influenced towards one of four archetypes, control, lust, immorality, or indoctrination. In order to receive one of the 23(!) "good" ends, you need to end up with D.va having a single maxed out archetype, two half maxed archetypes, or D.va with a half maxed archetype and seduce one of your coworkers (Sombra and Widowmaker).
You'll note that what I describe is more like gameplay and less like the story, but it's basically both in this instance. Each of the individual mind control events are rather piecemeal. There's some degree of an arc as each event is more extreme than the last and a mono-archetype path has slightly more direct progression than the alternatives, but overall the game is really 32 short D.va mind control events and five(ish) Sombra and Widowmaker events, leading to an ending.
Honestly, it's not too bad though. I liked some of the scenes far more than others but I don't regret playing the game overall. It helps a lot that the game is actually complete, which is almost an anomaly on this site. I probably would have five-stared it if the art had been just a little bit better. Some of the faces during scenes are... something.
Overall though, 8 Days with the Diva is a quick and dirty little game to get your rocks off with a couple of the Overwatch girls. While diving into the monstrous amount of Overwatch sex shorts online will certainly get you off quicker, I don't think you'll find your time wasted here.