I am currently working on an edit, sorry I haven't posted it yet, still a heavy WIP. You currently have hundreds of colors, which is overkill as well as many other things that bother me, but a picture says a thousand words so I will post it as soon as I get it close to what I want to explain.
Edit:
I did a few things here but gave up as you have way too many colors and it looks like you didn't pixel this. The black outlines really aren't needed and as you can see in a few areas look fine where I removed them. I can't really read the characters on the screen so I wasn't sure how to edit them besides removing that really dark black. Throughout your palette you have many colors that are nearly identical to a few others. Notice how I removed the black shadows. Shadows should not be black but reflect the ground that they are cast on. I edited a few buildings as well but didn't touch the ground much. Again, you have outlines over everything which I don't think so be there.
Here is a image with reduced colors, down to 32 colors. (Note I didn't finish my edits on this one.) I know there are a few details missing but that's because I used software to reduce the colors and didn't do it manually. As you can see much of the detail remains.
I hope this helps some.