[Admins]

Multiple tile layers are planned to be added to one of the next Graal versions. If a players goes below the second or third tile layer it could display the tiles partially transparent.
The tile layers still require some small scripting though, for specifying at which height the layers are (z) and to put the player at different z when going on the stairs.
For editing the additional tile layers we will need to finish the online level editor. Good is that the .nw format already supports multiple layers.