Heuristically guided search. :) For some nodes you go wide, for some deep, sometimes you retreat back up a few levels instead of exhausting a subtree (but you might come back to that subtree later), all depending on what the heuristic says is more likely to get you to your goal the quickest. A* is a well-known base algorithm for this, widely used in game programming to efficiently find the shortest path from A to B in the presence of obstacles etc.