The book is already funded. If you back the project, you will get your reward, and you’ll be contributing to possibly making it bigger. There’s a chance it might make the first stretch goal, which means 16 extra pages full of undead abominations for use in any GURPS campaign that needs monsters.
One of the classic complaints of many new and veteran GURPS players is the lack of a “proper monster book” for GURPS 4th Edition. Lots of books include a small sample selection and tips on making more yourself, but there’s no official “one-stop-shop” for ready-made critter stat blocks. And of course, this being GURPS it’s kinda hard to make a truly generic monster book, since whether a given monster is an impossible challenge or a mere speedbump depends on who your PCs are.
The Nordlond Bestiary is probably the closest we can get to that mythic book - a chunky selection of creatures suitable for Dungeon Fantasy campaigns. DF has a well-known starting point total and a known set of PC templates, you can easily know how the monsters are callibrated. And it’s also the genre that’s more likely to need a “monster book” anyway.
The book will be made for use with the DFRPG boxed set, but it’s also perfectly usable with the GURPS core books if that’s what you have. And since you know what sort of PC these monsters were made to fight, you can also adjust them for your specific campaign more easily.