Basically we have the normal rectangle maps, in each mission there will be a front line that could be anywhere. On your side of the front line you can move anywhere on the tiles but on the other side of the front line the border tiles can only be used by the enemy. You can see them but not move into them. This way you may never be safe on any side while advancing and still can take out enemies that are placed there. Hope this diagram clarifies the explanation.


