Oh boy, oh boy! I don't know where to start. First, you can't review this book without spoiling it (similar to "Project Hail Mary"), but I will try my best. If you are looking for fast-paced time-travelling sci-fi, stop reading this review and pick up "Recursion" wherever available. You will not regret the choice!
When describing the book to friends, I have to use a variety of comparisons. I tell them that this book is similar in mindblowing to "Blindsight" but closer to the "Dark" tv show. "Recursion" made me laugh and feel, got my heart rate up and left me thinking about fascinating concepts on multiple occasions. It was so good I couldn't stop turning pages.
The novel reads as a fast-paced detective-action movie script. I wonder if the author (like the author of "Martian" and "Project Hail Mary") wrote it explicitly to be turned into a live adaptation later. I also thoroughly enjoyed that one of the two protagonists was female without the "in your face" diversity-washing. It felt very organic and without any extra overpowering.
The ending does not disappoint. At first, you will be like, "nonononononono," but then, "oh, ok, I can sleep well now as the story is complete." Overall, this is a very short yet packed with action and exciting sci-fi concepts novel. I can't recommend it enough!