Again, a great article, but I feel like some of the general thinking behind heuristics is getting lost. Heuristics can be significantly more interesting than distance between two points. This isn't a huge criticism. In this context -- pathfinding on a grid -- complicated heuristics may not be needed.

When I first read about A* a long time ago I remember, for example, reading about how static summaries of chess board positions may be useful heuristics. Developing pieces towards the center of the board is often better, for example. To me, seeing this was an "ah ha" moment for heuristics: use them if they are cheap and (sometimes) informative, relative to the search cost.