Interactive Environments...
I got the idea for things that can be damaged, broken down, scarred, ect...
Walls can can be broken and crumble from fighters run attacking or mages using strong projectile exploding spells, ect...
Trees that slightly shake or make brushing noises and leaves falling when players are fighting around them or magic spells are shot at them.
When fireballs are shot at stone walls, it can leave scorch marks on the walls temporarily.
An island of petrified nature that can be destroyed like trees that grow quick (like monsters spawning) These trees would look kind of whithered, petrified (lil shiny) and when they're destroyed, there's a chance of a special gem dropping from the tree, which could be used for a quest or some other uses.
Stuff like this to make the game more interactive.