In the end though gameplay is the most important thing and that seems to be done well.
We mainly worked on gameplay, where tests often took longer than the same encoding.
For the sprites it was a common choice with the awareness that they might not even like it. I simply took advantage of the greater definition of the C64, while still remaining in Konami theme with the character of KV2.
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.