Cave Story HD Mod

that looks pretty nice! i'd make it a little lighter (or at least play around with the saturation/hue a little?) but i think it's a neat effect... subtle, but that's all it really needs to be

and yeah, it'll need to be playtested in waterway/ironhead's fight, interested to see how it'll look there

 

The switch port's decision to make the water more visually distinct from the water was a smart move but I think the water shade should just be taken on an area by area basis based on what the backgrounds the tilesets are paired with should look like.

If there's anything that might need adjusting in the style thus far it'd be the consistency of when you do and don't use the blurring, it's a bit all over the place here and in most anime backgrounds, etc. You're expected to do oil paints and gouache paints.
You also need to emulate the effects of ambient occlusion to properly sell the effect of depth at this high of a resolution.

The rocks in Cave Story being as tightly packed as they are means they almost always end up looking worse in ultra-high resolutions unless you're actively adding in more pebbles & cracks to account for the missing detail. CS's limited palette starts to fall apart once you're putting the resolution this far above what the eye is really conditioned to see.