If you are the adventurous sort, try expanding your project to add the following:
Add some buildings to the town
Set up some entry points for a building and work that into your navigation system, for example, a shop
Add some rocks to the scene and color each differently using a manual material, maybe even add a script to randomly set the pixel color in the shader instead of creating several materials
Add a new scene for the cave using another environment background, and get the player to travel between them