Oh, hey! It is your article I read in that thread! I have same question as to ptoing - what is wrong in my mockup (don't say "everything", please))) and there will be difficulties with realization on NES?
I hate to be a killjoy, but If you're serious about hitting NES restrictions you will likely have to redo a lot.
Backgrounds get one color you can use anywhere. Then, you get four sets of three colors. No 16x16 pixel region may use more than the 3 colors from any one set, plus that one color you can use anywhere.
Here is a screenshot of Super Mario Bros.:
Here are the sets of colors that screenshot uses for the background:
The blue at the top is the color that can be used across all the sets.
This is a breakdown of how the colors are used:
The blue grid breaks the image into 16x16 pixel areas. (Though the image is 2x for clarity). I pasted the number of each palette in the regions that use it. (I didn't do repeats, though. It's clear all the ? blocks use palette 4, so I only marked one of them.) Note that any area that is entirely blue does not have a number. This is because a solid blue area could use ANY of the four palettes, since that color can be used in any of them.
Now, here is a 32x32 portion of your mockup with a 16x16 grid (again, 2x for clarity):
I noted the colors used by each 16x16 region. You're using 5 to 6 colors in each region!
You only get set of 3 colors in each 16x16 pixel region + the universal one on NES. I know you didn't want to hear it, but there are barely any places at all in the mockup that use that few colors in a 16x16 pixel region.
Edit: Also, I'm confused, it seems like there are two versions of this. One that tries to be NES restricted, and one that doesn't. The one I used above has more colors than another one posted, but both are still over the limits.
To keep things clear, pick your sets of colors and post those as well. Then it's much easier for me (and everyone else) to see what your intended sets are supposed to be, and when you're going over. (Otherwise, I have to guess. And sometimes people use a different universal color than I expect and I guess wrong)