Well, that depends.
For a game like "Empire", you have two terrain types:
Water
Land
For a game like Civilization, you have about 8-10 different terrain types, plus two different specials per terrain type.
For a game like SMAC, you have 3 nutrient levels, plus 3 mineral levels (9 types), plus three resource bonus types (27 combinations) plus altitude variable from ~-3000 feet to ~3000 feet, plus a whole HOST of terraforming types... (Boreholes, Echelon Mirrors, Water Condensors, Solar, Forest, Fungus, Farm, Nutrient Enrichers, Kelp Farms, Tidal Generators, Deep-Sea Mines) Plus you need to keep stateful information about terraforming as it progresses on a square.
Oh, and then there's special terrain like the Borehole Cluster, or Mount Planet, or the Uranium Flats... ;)
Yeah, there's a lot there.
After 9/11, Bush made two statements:
1. "Terrorists hate America because America is a land of freedom and opportunity."
2. "We intend to attack the root causes of terrorism."
Sounds like everything is going according to plan.