those kind of sprites are doable with ease even on a simple msx1. What do you mean of "greater definition of sprites"?
those sprites are far smaller than the maximum width of a sprite on c64. 24px.
I also see that on the main charater you used 3 monochrome sprites.
No! Main character has two sprites, one hires to frame and the other multicolor, a technique often used on the C64. For the main design I based myself on the definition 16x16 as on MSX, also to fit into that of the backdrop, where the active part of the game is 256 x 192 instead of 320x200. The greater definition of the C64 sprites, or 24x21, I used to draw the main character in case he had the pickaxe or the dagger without adding a third sprite, so they are always two sprites with or without an object.
However in reality for the design I am not the only one to have based myself on KV2, before us also Retroworks did it with the Zx Spectrum version.
Looks very good. Great job! A good reason to get my C64 from the attic 
