PixelBasher doesn't do any automatic shading. What you see in the video's posted on social media: It's more like overlaying gradients or textures and then limiting the number of displayed colors. PixelBasher does ship with a few fancy dither patterns to simulate rust, dirt, etc.

In the end it's only one of the tricks that PixelBasher has. If you want to test if this method could work for you, I think you could also manually try to do something like that in another application.

Thanks for the explanation! I think Appimage is indeed the way to go. I'll look into it!

Eventually the goal is to have all sorts of color tools in the application. Per object color tint, global color palettes, etc. For now working in grayscale solves a lot of problems on my end. Sorry that it's a hassle to get the output to a specific palette at this point. I've gotten good results with blending color overlays on the output, but if you have a specific palette there will still be a lot of  work in color replacing.