Here is my edit, but only of the first screen (didn't think of taking other landmarks as well.)
I would have kept the grass relatively bright, but because the dirt walls have black as a significant part of their coloring, I chose to keep the browns dark and darken the grass instead to get comfortable contrast.
The portrait was a challenge since it affected the text box and the mat as well. There needed to be a lowered contrast between the colors that make up the blatant airbrushing on the text box so that not only does it look better, but it makes the text more readable as well.
My biggest regret is that the house lost its red colors. This is my fault though, for reducing the amount of colors too hastily (wanted to incorporate the dirt and the grass even further).
At this point the biggest improvements would come from actually editing the pixels, though I choose to just edit colors.