Re: colours, I do think that there is a bit of a feeling of a "piss filter" because
everything is rather yellow. Try hue-shifting your shadows towards blue:

While I was at it, I also tweaked your browns to add a bit of hue-shifting, and edited the cave entrance to remove some banding and give it better indication of the light hitting the floor.
I forgot to give feedback on the road corners. I like the rounded corners more!
Do you want a blocky stylised look, or are you aiming for something a little more organic/realistic? If it's the latter, consider making the cliff and road edges a bit more irregular and wavy.