Zone of Control is a very important concept in the Fantastic War because it effects movement and combat. The Zone of Control rule is:
Any minor unit exerts a Zone of Control into any adjacent square into which it can attack.
Any unit, major or minor, that moves into a Zone of Control must stop and attack. You do not necessarily have to attack the unit whose Zone of Control you are in.
Which leads us to the green frame. Every once in a while, when you enter a Zone of Control, your units will get a green frame instead of a red one. This means that you've entered a Zone of Control of at least one stack, but there are multiple stacks you can attack. In this case the computer needs to know which stack each unit wants to attack. Do this by selecting "Allocate Combat". Also you will not be able to end your turn (End Turn will be dimmed) until all green framed units have allocated their attack. If you can't remember where you need to allocate combat, you can use the Find Combat from the Game menu.
Also if you did not enter a unit's Zone of Control by movement, you may move and you do not have to attack. However, if you subsequently move into a Zone of Control, that unit's or any other unit's, all the above restrictions apply.
