I think most mods far have only modified a txt file to reduce the overall movement rates.

Find the file descr_battle_map_movement_modifiers located in the Total War\Rome - Total War\Data folder.

The default values are:


HTML Code:
climate			default

grass_short		1.0
grass_long		1.0
sand			1.0
rock			1.0
forest_dense		0.75
scrub_dense		1.0
swamp			1.0
mud				1.0
mud_road		1.0
stone_road		1.0				
water			0.6
ice				0.5
snow			0.75

CBR