You did a great job trying something new!
Maybe a suggestion: I really do believe it doesn't need more color. The more toned down style is really cool. What would however step it up a lot would be shading via normal maps and actual lighting. I don't know what engine you are using (if any) and I don't remember if there was a splash screen of one. But most mainstream engines should support nice 2d lighting with actual shadows and all.
This would look really cool!