This.
Currently you can all spot enemies within a certain radius, I don't know if forests, terrain, type of party has any affect on the radius but it's not significant either way.
A good idea is creating more dynamism on spotting. Like
@Julio-Claudian said, having chance of negating being spotted determined by skill, terrain... even when inside the normal spot radius.
Having spot radius for friendly troops being the highest; For neutral parties, medium radius; And for enemies, according to some skill on spotting and tactics of their party, a radius between the medium radius and a smaller radius.
As for ambushes, parties would require more skill or special skill to be able to evade the small spotting radius of the other army. Let's say if some party with the ambush ability manages to get inside that small spotting radius undetected, then they stay hidden as long as a "spotting threshold" is maintained by the attacker party.
In more practical terms lets say a
blue army is passing through some trees, on the opposite way comes a
red army, which as more skill in tactics, spotting and the ambush ability. As they come closer to each other the
red army spots the
blue army while going undetected and proceeds to follow and attack the
blue army.
- Situation 1: While in the trees, the red army (being undetected) manages to close in and ambush the blue army.
- Situation 2: While in the trees, the red army remains undetected, but it's not fast enough to catch the blue army as he changed direction. The red army ends the chase still undetected.
- Situation 3: While in the trees, the red army fails to catch the blue army, but red is in his small spotting zone. As both of armies (red still undetected) exists out of that "tree zone" and enter an "open zone", the terrain advantage progressively fades as both get further away (red still undetected), until the threshold where the blue army is able spot red again. Now as the chase still continues, red is no longer able to ambush, as he is detected by the blue army. The red army still got very close and gets to attack as normal.
Note: The ambush ability is not the same as the ability of renaming undetected. Let's say with only just the ability of renaming undetected you could remain undetected, for example, inside a medium spotting range. The ambush ability would enable parties to get inside the small spotting range undetected and thus performing the ambush (in which, for example, could spawn the attacker in proper formation really close to a defender in a messy formation).
