Alter Aeon Online Help

Keywords are:  'terrain'

The 'terrain' command indicates what type the local terrain is.  It can
be light forest, a mountain, a building, a cave or even underground.

Although a room's terrain can typically be extrapolated from its long
description, this command exists to remove any doubt.  It can be important to
know what the local terrain is because certain spells only work in certain
terrains. Also, certain types of resources are only available in certain
terrains. For example, you're not very likely to gather mesquite wood in
a swamp, or to gather water lilies in a desert.

Terrains are loosely grouped together into biomes, such as woodland or
permafrost. Terrains in same biomes will generally yield similar resources,
though in differing quanities. See 'help biomes' to see more information
on different groups of terrain.