So many great pictures! What a motivation-boost. I am working at my limit here and it was so hard for me to push the pixels a bit further. At least I like the result now. I wanted to concentrate on the tiles, so no raster splits this time. (They do not help much in this pic, anyway)

@PypeBros: Rounded edges, changed top-hilights, no roots climbing up. (thx for that one) Although, I like everything about Arachne's mockups, I couldn't fit these vines in there.
@Helm: These dark dithered patches are excellent. Especially the brown version; the blue area looks a bit like an underwater scenario. I tried to implement such patches: Hires blocks in the inside area, and multi color wide pixels in the outside area. I am not sure about the green dither. Your green blocks look better, but they are also more noisy. I also have the same feeling about my green leaves in the outside area.
@Carnivac: Hey, the blocks inside are hires, but do not have single pixels. So what does your pixel-eye detector say here?

I didn't like single hires pixels on the C64, they always caused some color distortion on my TV. I guess that is why the C64 font has double pixels.

Here's a variation of the hero: Cyan shirt, brighter shoes and red outline. That works well in "the cave", but might cause some issues in other mockups.
@ptoing: I think the maps allow full height sprites up to 19-20 pixels. (reserving 1-2 pixels for the running bounce) With your big helmet, he looks even smaller. But I like the helmet. The hero could maybe start without hat and this could be a powerup.
@bladeJunker: The hires pixels are there with or without raster splits

These splits just add 1 or 2 extra colors. I don't think this is a big deal, because the game would need splits anyway to show more than 8 sprites.
@Grimsane: I like the big-head-hero, too. But I shrunk his head because of the running animation. But this is a different story. Anyway, the head-size is not final... Cool overall outfit!
Adam: Wow, I also tried to darken his other side, but failed. This sprite is awesome!