thanks for all links! not sure what happened to the site, i couldnt visit it for a while.

Oh, I see! I thought it was a hole into the ground because of its shape. Try dulling the left and right edges. There's not much reason the tunnel should taper so much. Your latest edit has a nicer shape than before though :D

I think you should try to emulate what's in the the ant farm image you showed. Notice how the light is coming from above, so the floors of the tunnels are lit up, but the ceilings are in shadow.

As for whether you're starting in the right place, I don't know! I think 16px tiles are a great working size and I tend to use that size. Small enough to allow for interesting inter-tile interactions, large enough to include a lot of detail. However, it seems that your struggles aren't so much with size, but with non-pixel-exclusive concepts like lighting. You may want to practice that stuff in a medium you're already familiar with. I recommend reading Arne's two tutorials: pixel art tutorial, general art theory tutorial. A lot of the knowledge that goes into making a good pixel art piece is not pixel-art specific, so don't forget to study beyond just pixel art.

Thanks again! These are very helpful

I think a lot of the trouble I have (other than inexperience, lol) comes from the fact that in this game, you're actually seeing a cutaway of the dirt rather than a hole that goes top to bottom   www.diarystore.com/sites/default/files/prairie_dog_house_air_conditioned.jpg  (sorry if the link doesnt work, haven't looked at how to do that yet) Technically, this view doesn't really exist in real life, apart from ant farms or something similar.  It's basically an orthnographic view.

Is there any way to simulate this instead, do you think? I'm going to take your advice on the lighter color and shading while looking at something like this: polarcoordinate.files.wordpress.com/2015/10/antfarm2.jpg   let's hope it works out

Also, as a side question, am I starting in the right place? I'm starting with 16x16 sprites and tiles, then I'm going to work my way up

The detail file is for when your whole piece is too big to fit as the preview image. Since yours is smaller than 100x100, you don't need a detail file at all.

Your new shading doesn't really give any sense of depth, it just reads like noise. Remember, the dirt in the hole would be lighter near the top/edge and darker down below, and that the black part of the hole we see is mostly the far wall. Here's a wireframe of a similar shape to help you imagine it in 3D.

Here's an edit with a suggestion. Instead of highlighting a bunch of small clumps, I highlighted some larger clumps leading down into the hole, so show the slightly-angled walls, and I had them get narrower towards the bottom to show them getting less light.

If the NES restrictions allow it, you could even add another highlight colour to the tops of the rocks.

thanks! I see your posts a lot, you're really helpful

I'm guessing the pre-zoom is the optional larger upload option, I didnt know the zoom button did it anyway- good to know!

I'm not entirely sure how to use your advice, but I'll do my best and re-post it

You don't need to pre-zoom your art for PJ, every submission has zoom buttons underneath it.

The hole doesn't look very holey, I think showing some bits of light (using the browns) in the hole would help. Having the hole fade from the edges towards black would also help, the hole's edges look unnaturally sharp.