One test image was Phoenix849's (Sorry man!)

I actually didn't check it for 16px regions yet, so I presumed it contained mistakes. It's still unfinished, so I'll be manually looking through when I merge these 3 mockups into one. Right now it's in 3 different Pyxel Edit files, where you can't switch grid from 8px to 16px without resizing tiles themselves.

Considering my shallow knowledge about NES, could you also link or talk about palettes? Why choose Bisqwit's over Nintendulator's?

Also, finally played Castlevania myself first time ever. Keep falling to death on medusa heads on 2nd level

Okay, it seems I've underestimated the restrictions due to being inexperienced with NES tilesets:

1. Does HUD also count towards limits? That's why interface and walkable platforms are constantly red/orange?

2. Does the whole first level (VGMaps link) have to use only one palette for outside AND inside areas? Just when I thought I was going to make some sweet forest graphics outside of the castle

Good timing, I was just itching to do some NES mockups, though have almost zero experience with it. Also not a Castlevania player, just wanna pixel something nice.

Here's what I've manage to do over evening. Image cropped from VGMaps. Palettes are all over the place, those diagonal stairs unexpectedly screw me over due to 16 x 16 pixel region color limits. So yeah, it doesn't follow restrictions currently. I have to rethink the whole color scheme all together. But I feel inspired, and want to play with different areas. Really excited to see how far you guys can push those graphics.

I'd also like to share these: http://imgur.com/a/kUrra

Saw this kUrra album earlier and was incredibly inspired by this playing on NES limitations so perfectly. I'd say it's my favourite NES mockups I've ever seen. I'd like to post some sweet stuff by ptoing I've discovered just yesterday. I feel it is relevant for Castlevania thread:
Spoiler

Little late with T38, working hard to finish it right now.
DONE!

T3 please. - DONE!