Needs to be made as anime
Seriously, this kind of story is just MADE for the anime medium. The characters, the creatures, the storylines, the tentacly mutants/monsters, and the villains, the wanton violence and bloodshed- ALL PERFECT FOR AN ANIME SERIES!
THIS NEEDS TO BE DONE!! There are enough books in the series to cobble together a decent story arc for a single season, or even just a mini-series.