Alter Aeon Online Help

Keywords are:  'set room terraintype'

set room terrain <type name>

Terrain type is used to describe the land in a given area, independent
of room flags.  Available types are:

Type            Description
-----------------------------------
notset          default for all created rooms
none
indoors
town            city streets, in a town or city
field           grassy field
lightforest     some trees
thickforest     many trees
darkforest      dark evil trees like DFE
taiga           thick, cold forest
swamp
plateau
sandy
mountain        mountainous, rocky, high altitude perhaps
rock            rare - on a lava flow or very large stone construct
desert
tundra
beach
hill
dunes
jungle
ocean
stream          shallow stream - shouldn't require swimming
water           river or lake
underwater
underground     caves, tunnels, etc.
air

NOTE: not all terrain types can be set on clan rooms, for example
underwater terrain is not allowed so you can't accidently drown
your clanmates.