This is an isekai without the isekai. EV3 (later Evelyn) wakes up in a test tube in an abandoned lab with a system and the quest to devour the others "born" with her to grow stronger. This sets up her drive to grow and become stronger with the unspecified background that she's pretty much amoral and power driven. So it's not portal fantasy (isekai) but it has aspects of it due to memories and judgement that originates outside of the character's base circumstances. Anyway, good for a power fantasy, not so great for the character, right?
Only, the author does a pretty good job with the characterization, too. You see, she isn't without some guidance. She doesn't have memories, as such, but her creators have gifted her with worldly knowledge. Language, survival skills, cultural background, and basic system things like classes, traits, and skills. So she is making relatively good choices and her plans don't suck. And bonus, once she encounters people, she isn't a mindless killing machine and can navigate social situations without the fish-out-of-water gaffs. She experiences kindness. And betrayal. And has a chance to develop "allies" that she invests in. In other words, she forms a foundation for thinking beyond mere transactional utility and potentially a foundation for cooperation and even friendship.
So it's a power fantasy with a protagonist who is figuring out her own motivations and what she will and won't sacrifice for. And I enjoyed it more than a little.
I had two things holding me back from complete immersion. First, the author gets bogged down a bit during action scenes. It's bad enough that Evelyn gets in so many fights where she's completely outclassed, but each sequence includes both her decisions and analysis even as she's in the midst of duking it out with her life on the line. I actually skimmed entire paragraphs in the middle of some of the later fight scenes it was so pronounced.
Second, it got a little old with her being completely outclassed by forces hunting her for her nature and origin. It was frustrating the couple of times Sapphire shows up and just plot bombs the story. And I hated them even more when they became PoV sections in the epilogue where we see them conspiring and scheming. It struck me as unnecessary and "extra"; intrusive in a way that detracted from my enjoyment and nearly to the level of not wanting to pick up the next (because the foreshadowing made me groan a bit).
In the end, I'm calling it four stars and admit that I almost certainly will pick up the next. I hope it keeps the best aspects of what I enjoyed, though the prognosis isn't good.
A note about Chaste: There's a completely left-field attraction pair-up but no shenanigans ensue. So this is fairly chaste.