The ids will identify each node. When the player touches a location to go to, the program can check if the node is in one of the "adjacency sets" of that node. To do so, a GameBoard can have a hashset of all the nodes on the board and the id will basically serve as a key. In the actual implementation, we'd also have to map locations on the screen to nodes, so that node (the value of the location map) would serve as the real key.