Its because of gameplay and graphics.... theres a vast gulf there.
^ this is not even remotely close how gorgeous Ori and the blind forrest looks.
Have you seen Hollow Knight in motion and with sound? That screenshot doesn't do it justice at all. Ori may have a few more flashy 3D effects but at least Hollow Knight looks visually cohesive.
But let's not kid ourselves, game quality has absolutely nothing to do with the different popularity here.
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