Path finding, A*, snakes, routes.
Service oriented architecture. Path finding logic will be used my management objects to decide what paths to take. People, Animals and even rides will need to seek new paths as the game changes. Free floating ships and open road vehicles are other examples moving objects needing path finding.
Decision Maker
Core Objects for collecting information walkways, roads, queues, ramps, accessible grounds and waterways, entrances.
All objects are places in 3D space and elevation must be considered in travel.
Remember the grid is only there for terrain and visual purposes, objects are not confined to the grid.
Placed objects will have a bounding box or sphere that must be considered.
Bounding boxes and spheres should have a method to test a ray for penetration into that space.