Heavenly Sword, Enslaved, and Hellblade exist as a sort of unofficial trilogy; Hellblade is so-called because it is a direct reference to Heavenly Sword – a declaration of unfinished business.
“In Heavenly Sword, Nariko’s sidekick Kai could see things – she was living in another world of sorts. And so the concept was, what if she grew up? What would she be like? That’s where that idea for Hellblade came from – if we had another stab at Heavenly Sword but in a different world, in a different universe, what would it look like?