No, this isn't a typo or some misled joke about HGttG. At least, not by me: the author was clearly referring to that book with the title. It's a book that was published in Hebrew about 2-3 years ago about serious Halachic answers to ridiculous sci-fi/fantasy questions. If that premise sounds vaguely similar to something you've heard once - it might be because this book was inspired by "What If?" by Randall Monroe.

As a Jewish fan of Fantasy who especially likes Jewish Fantasy, I liked the premise of the book, which raises the question why I only read it now. And honestly, I don't have much to the side of a proper answer. I just... didn't come around to buying it until lately. Part of it is because it was only available for sale in the website of a publication company I've never heard of, and another part might be because I was slightly dissappointed by the samples I've seen. Either way, I have read it now, and was somewhat disappointed.

The book did touch somewhat interesting topics. It didn't feel like it delved deep enough into them, though. One of the great things about the book that inspired it was how deeply it delved into the physics of the situations given. And it's possible to do that with the Jewish Halacha, too! There are many thick books of responsa discussing Halachic questions, and the answers can be very long sometimes. But this book doesn't give much outside of listing some opinions without diving too deeply into the exact nuances and reasons different rabbis had to have their opinions, and it felt... somewhat shallow.

It is possible that this was done in the name of accessibility. The average reader, after all, isn't necessarily interested in the exact details of a random halachic question. A Yeshivah Bucher might be able to follow a complex halachic discussion, but not every person interested in reading this book is going to be attending a Yeshivah. It's also possible that I, being relatively inexperienced in studying Jewish religious Responsa literature, am simply wrong in my assesment of what such a book should look like. Or that I am taking this too seriously.

Either way, the fact remains that I don't think this completely fills the gap that exists in Jewish Fantasy - a gap I don't believe I have the talent to fill, either.