Constrained and more optimised route finding * Track routes so we can see if we have gone straight for too long * Track multiple routes so we can use a non-optimal route to X if it makes another route to Y through X possible (e.g. optimal route takes three consecutive steps to X, but then has to turn, whereas a longer straight earlier and two consecutive steps to X gives a much better next hop to Y) * We have a start point, so only include the nodes from the search front in "unvisited" to avoid looking at lots of irrelevant nodes