Well the NavMesh used by SteelBeasts in particular is something, i do not fully understand. I mean, how SB uses it.
With that explanation from unity3d, it is starting to get clearer
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A navigation mesh (also known as the Navmesh) is a simplified representation of world geometry, which gameplay agents use to navigate the world.
Typically an agent has a goal, or a destination, to which it is trying to find a path, and then navigate to that goal along the path.
This process is called pathfinding.
Note that Navmesh generation (or baking) is done by game developers inside the editor, while the pathfinding is done by agents at runtime based on that Navmesh.
In the complex world of games, there can be many agents, dynamic obstacles, and constantly changing accessibility levels for different areas in the world.
Agents need to react dynamically to those changes. An agent's pathfinding task can be interrupted by or affected by things like collision avoidance with other characters, changing characteristics of the terrain, physical obstacles (such as closing doors), and an update to the actual destination.
http://docs.unity3d.com/Documentation/Manual/NavmeshandPathfinding.html
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