Terrain

Summary
Terrain types in CAOS are tremendously varied from the desert sands of North Africa to to the darkest forests of the Hürtgenwald. Broadly speaking, terrain is separated into two different types - hex terrain (terrain inside a hex) and hexside terrain that exists between the edges of hexes.

Different hex types have different OPC costs to enter. Some even effect combat by modifying defender combat value, reducing defender casualties or by lowering the efficiency of incoming barrage. All of these modifiers are cumulative, so a unit moving across a minor river into a forest would pay the OPC cost for both. The same is true for the defensive modifications, a combat taking place across a minor river into a forest would grant the defender a +100% combat modifier.

Terrain and OPC Cost
Different terrain types have different Operational Capacity point costs to enter or to attack for both infantry and mechanized units. For instance moving into a forest hex costs 5 OPC points for a mechanized unit but only 3 for an infantry unit. Some hex and hex side terrain is even impassible to mechanized units. For example mechanized units cannot move into mountains or over escarpments without the aid of a road or track.

Defensive Combat Modifiers
Terrain may also affect combat. Some terrain such as Forests provide a defensive combat bonus to the defender. While Salt Marshes actually reduce defender combat value.

Die Roll Modifiers
Other types of terrain such as woodlands and roads provide a die roll modification (this reduces defender casualties).

Artillery Bombardment Reduction
Dense Forests, Forests, Mountains and Cities all reduce incoming barrage effectiveness. However they do not reduce the effectiveness of artillery firing from inside these hexes.

Roads, Tracks and Bridges
Roads, tracks, bridges and temporary bridges all modify unit movement between hexes.

Roads
Roads reduce OPC cost to 1 while moving down a road. Additionally roads negate terrain movement costs, for instance a road can allow a mechanized unit to move into a mountain hex. Furthermore units may stack up to 6 stacking points high while moving along a road, discussed in greater detail in the stacking article.

Bridges
Bridges are roads that cross rivers, they function identically to roads in all ways except that they can be destroyed and repaired by engineers.

Tracks
Tracks negate terrain OPC cost. Thus allowing units to move down tracks like it is clear terrain. Like roads tracks also allow units to move into or across terrain that they would usually be unable to traverse. Such as mechanized units in mountains. Tracks do not benefit from a movement stacking bonus.

Temporary Bridges
Temporary Bridges can be thought of as tracks that engineers can build across rivers. They simply negate terrain and allow units to cross rivers, Temporary Bridges can be built across both minor and major rivers. They will continue to exist as long as there is an an engineering unit adjacent to them - either friendly or enemy.