Change objects icon_state in game in Developer Help
obj wall icon = 'turf.dmi' icon_state = "wall" density = 1 verb change_icon() set src in oview(1) src.icon_state = "rock"
obj wall icon = 'turf.dmi' icon_state = "wall" density = 1 verb change_icon() set src in world src.icon_state = "rock"