Try colouring the tents a darker shade of green to separate it from the terrain itself. Maybe colour the walls and the tower a brown or a grey to represent wood or concrete as well, because they kinda look a little strange being green. Adding trees and some other foliage would also be a nice touch, as well as using much larger bricks for the walls, as it can seem spammy for being loads of little ones.
An interesting start though.
