I really like the story, while it it is an isekai, it doesn't really feel like one. The story could work with MC being from that world. It is definitely quite dark, so if you are not a fan of dark/gore just don't read it, it isn't like horror gore, but it has its fair share of it. Not too much of the manga exists, but i very much enjoy how the world is set up, and it reminds me of a lot of the grim things that have happened in humanity's past, but in a very appropriate manner. It has elements of revenge in thestory, but i don't feel like it overwhelms other character motivations and is just a reasonable reaction to what happens to characters around them. As a warning i have only read up to chapter 28(the latest chapter as of now), so in future some things in tone or characterisation might change for better or worse.