You'll likely have to kill some of your darlings here but it'll be in the service of a better game.
Agreed. I'm glad I tried the more realistic rendering, just for learning purposes, but I don't think it fits the game.
Here's another attempt at the dog in the truck. I like it better than the first, but I still think the pose is weird:

I also tried refining the shepherd's portrait a little more. It's still sketchy, but i think stuff is defined a little better:

EDIT
Painted over the card from my old thread to try out a more sketchy style, with more more vibrant colors. This might be a way to go. More like a screenprint.
EDIT AGAIN
Painted over the shepherd with a bigger brush and one extra color:

Also messed with the colors in the ending. Here's how it looks with all the layers:

In the game,all the layers scroll, the truck bounces around, and the dog will be animated.