The Anomaly is very much speculative fiction in the sense that it’s not about the anomaly itself, and it’s not science fiction in the sense that there will be a scientific explanation. It simply has something strange happen and then explores in detail how all the characters deal with it, which is a different way to approach storytelling.

If you’re interested in books like that, Jo Harkin’s Tell Me An Ending fits the bill— you’re contacted by a company, it turns out that you paid not only to have a memory erased, but to have r your memory of erasing the memory erased. Due to a lawsuit, they have to offer you the opportunity to get your memory back – but you can’t know what it is beforehand. Do you trust your past self? Or does not knowing what happened to you drive you so crazy you’re willing to re-traumatize yourself/destroy your marriage/whatever the consequences would be that your past self was trying to avoid? Then it follows the people involved as they struggle with the decision/consequences.

In more typical sci-fi, Adrian Tchaikovsky‘s Doors of Eden explores what would happen if we had parallel earths where evolution had taken a different path. Maybe that’s what you’re thinking of – so… what would happen if squids became dominant and ruled earth? What would happen if rats did? Sounds crazy but it’s a really great book.