I went with the classic ww2 theme for my entry... As you can probably see its inspired by Metal Slug one of my favorite arcade games of all time. I decided to go with a bit more realistic looking vehicles though.
I'll probably update this as suggestions come in, I'm not entirely happy with the middleground (ruins and stuff)... Oh yeah, 38 colors.
pretty big update here.. spent a while on all these great suggestions and thus redid the whole sky and added some ruins in the foreground. I think I made it as confusingly detailed as I could get
This brings me up to exactly 40 colors. Oh and if you want to see the old version for comparison, check it out here