A proposal for a simplified solution: walls could be garrisoned by archers, like other structures. User selects an archer, player orders him to garrison a wall segment, archer approaches it, then wall he appears on the wall. When wall is destroyed, archer also dies; when archer is killed, he falls from the wall and disappears. The solution would be simplified because: - archers cannot walk on the walls, their position would be fixed (they are "part" of the wall) - this feature would be restricted only to a unit type (archer) - need for additional animations is limited, because all animations for archer already exist. Only "enter" (archer climbing a stair) and "exit" (archer falling) animations could be made, but they are not so necessary at a first phase of implementation. A second, harder, possibility: - archers garrison the entire wall, not only a segment - climbing and falling are only animations - a separate (flat) heightmap is created, corresponding to the entire wall, on which archers can walk. Connections between terrain heightmap and this one are not necessary: they would be limited to garrisoning/ungarrisoning aminations.