This, mostly. It completely betrays the visual style of Demons Souls. It makes outer Boletaria out to be some ornate Gothic lavish castle instead of a utilitarian Romanesque fortress. It makes everything super overgrown with vegetation as if the colorless fog has been leaving everything and everyone to rot for decades, it makes every enemy more generic, it generally gets it entirely wrong. Flamelurker looks like a Balrog, you get absolutely none of him being a twisted former human like his old design. His boss arena looks way more gamey too, like its God of War or something. Like the Armored Spider now having a wooden floor underneath him even though he used fire attacks, its just nonsense visual changes that had no thought behind them other than looking good that change your read on the world and the types of people who inhabit it.
The music exemplifies this change of tone too, Demons Souls did not have a bombastic and epic soundtrack because it was not an epic tale, it wasnt a hero vanquishing foes, it was you trudging through a decaying world and killing Demons only by the definition youre given for a demon, really brought to a head when you get to Maiden Astrea more than anywhere else.
Its a total hack job only meant to be a tech demo and its remarkably depressing that this is what passes for preservation of one of the most important games of its generation. A game that actually COULD USE some updating, too, but not like this.
I will agree that changing the music was baffling as fuck. This does bother me whereas the other design choices dont really.
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"Our selves are something we create, not discover."