I don't think that the problem with this movie is that it's a "ripoff", honestly that's just lazy criticism at its finest. This film just feels like one because it naively thinks it can recreate excellence simply by being derivative, and hide its flaws/excesses behind its identity as a "tribute".
The world of The Spine of Night was evidently intended to be a world of high fantasy comparable to the works of Ralph Bakshi, Moebius and Richard Corben, but instead of feeling like a faithful homage to the art and ideas of these creators, it comes off like a lazy mishmash of all the most easily identifiable and sensational tropes associated with their works. Gratuitous violence and nudity? check. Evil Wizard? check. Uncanny anachronism? sure. Incomprehensible, psychedelic cosmic beings? they're all here.
But in the stiff, poorly choregraphed battles, with their low stakes and predictability, the visceral gore feels boring, childishly decadent and unnecessary. Nudity, partial or otherwise, does not ground the barbaric, primitive setting as it often can, the only purpose it serves is to gift us with characters who aren't garbed in the ugly, unimaginative costumes that saturate the film. The villain is painfully one dimensional, given the disorientingly swift manner in which characters are introduced and disposed of in this film, I was praying the entire time that the same would happen to him. No dice.
It feels almost like they rotoscoped this movie just to say they did, as the animation does it absolutely no favors in increasing immersion. I will give it to them that rotoscoping is an insanely expensive technique to employ for film, and the constraints of their budget probably had more to do with the awful art than the skill of their animation team. Maybe if the production wasn't so fixated on resembling successful films of the past, they could have succeeded in at least one aspect in their own work, by using more practical and appealing modern methods.
The worst part of this movie is its message. In an attempt to mimic the high concepts that exist in their source material, the creators decided to go with the most pseudo-deep, philosophically braindead perspective they could: nihilism. The whole narrative essentially boils down to the classic "we're all just dust in the wind, maaaan."
What a disappointment... it just goes to show you, even if you give someone the finest ingredients and a meticulously detailed recipe, if they don't know how to cook, whatever they make is just going to taste like trash.