An alpine village or dilapidated ghost-town at the base of the mountain increases depth and contrast. Adding LED white and flame lights to the buildings adds warmth. Trees (or cactii) emphasize the rugged, hilly terrain. Safety must trump creative details though.
The mountain can be constructed many ways. Plywood sections stacked like a contour map is especially rugged and effective. Intermediate contours can be routed into sections to create smaller steps as desired. Edges can be softened further by routing with a roundover or chamfer bit - even sanded to a smooth finish. Chiseled blocks, doweled and glued, could be used for rugged peaks and overhangs. Sharp chisels, eye protection, and a first-aid kit are recommended if you embark down this path...
For transport and stacking, the portion above the 2½" level can be separated and set on the mountain base using steel or wood dowel pins for alignment and stability. Lights can be added in the ‘ceiling’ of the tunnel. A miniature mine train and shaft entrance could be incorporated and lit too...
