I posted this idea of mine on the D-list a while ago, I just repost it more because I'd like to discuss with other players in this forum.
Currently every region has a terrain type: city, rural, badland etc.
I'd like that units can get specializations in fighting on a certain terrain. This specialization gives a little bonus in terms of CS when the unit is involved in a battle that is occurring on that particular terrain.
In order to get a specialization the unit has to train on that terrain for a certain time. Another option appears in the Training panel, something like "Terrain training" and it costs like the Heavy training in terms of time/gold.
A unit can get more specializations so a troop leader is stimulated to take care more of his unit. For example: nothing is going on in your realm, rather than just sit down and do nothing maybe you can go to the nearest Mountain region and do speciailized training there so your unit will perform better on that terrain, no time waste and more "coolness" for your unit.
The specialization can be a "yes/no" or scaling or whatever. I'd just love to give more depth to my unit.