We're continuing this ongoing saga of different game algorithms using the simple game Color Walk. In the last post we started exploring the fundamental graph search algorithms with breadth-first search (BFS), because after all, the full set of move choices and resulting board positions of any game can be arranged as a graph. After looking at BFS and finding that we can nominally improve the search for shortest number of moves, on average, it's time we look at the close sibling of BFS: depth-first search (DFS). We'll quickly run into performance issues just like we did for BFS, but let's see if we can come up with a reasonable way to limit DFS so that it can be a useful algorithm.