Here I implemented largely bolded like text for stones and for the gate I used a lighter approach. For the dark stones I used dashed lines and for the light rocks, I used curved lines. To finish up used zigzag lines intersecting to formulate a 3-dimensional vibe to its shape.
Final work
You did a wonderful job capturing the purpose of this project. You see simplicity and expression tackled well, and you also did a great job translating the mood/color. Looking at this makes me wanna revise mine, but you live and you learn!