At the start of a game, you will need to have a look at the areas of terrain on the tabletop and decide how difficult they will be to traverse. Don't panic! There's a list of examples below. It's best if you can agree the terrain with the person you're playing against, but you can always roll dice for any areas you're not sure about.
Terrain is classified into three types: normal, difficult and impassable.
Normal. Grassland, crops, moors, most hillsides, streets, buildings, gantries, ladders, steps, fields, open woods, sparse brush or bushes, sand, rocky plateaus, ice sheets, scattered rocks or monoliths, low walls, most streams and rivulets.
Difficult. Sand dunes, loose ash or clinker slopes, steep hillsides, thick mud, dense or tangled woodland, thick vegetation, jungles, deep snow, marsh, peat bogs, waist-deep water (or other harmless liquids), ruins and craters, as well as vehicle wrecks.
Impassable. Very steep slopes and cliffs, high walls, bottomless dust pits, geysers, lava, swamps, tar pits, sludge pools, toxic waste, very deep water.