Terrain in Imperialism and Imperialism 2 includes a range of landforms from mountains through forest and plain to desert and tundra.
Most of the tiles that produce anything can have the quantity doubled or trebled by application of the appropriate technology with the appropriate civilian specialist. Scrub forest is the exception: just one unit of timber for ever.
Mountains can be among the most lucrative of the tiles in anyone's empire, because some produce treasures such as gold or gems (with or without less exciting minerals).
Terrain has an effect on one's ability to construct railroads (and in Imperialism 2 initially roads). Details differ between the games.
Imperialism
- Main article: Terrain (Imp1)
The other tiles that initially look bare in Imperialism but may be very valuable after a prospector spends a turn there are desert and tundra, each of which may produce oil later in the game.
You do not see mineral resources on tiles outside your empire until you have personally prospected them; but you see developed mines and oil wells everywhere.
Imperialism 2
- The specific article has not been created for (or "Terrain" is not part of) Imperialism 2
Desert is potentially the most valuable terrain in Imperialism 2 because it may hold diamonds.
Trade Empires
- Terrain is not present in (or the article has not been created for) Trade Empires