eulerize
Upload a picture of a map, trace the streets as a graph, and Hierholzer's algorithm will find a closed walk that crosses every edge exactly once — a one-stroke tour, if the graph allows it.
built for a hike: @eternalism-when walked a Eulerian tour of Wallington's named streets.
draw: tap empty space to drop a point; drag from one point to another to connect them (dragging to empty space drops a new point there too). Get near an existing point and it magnet-snaps — watch for the teal ring, that's your drag locking onto it, handy for clumsy fingers on a touchscreen. erase: click a point to remove it and its edges, or click an edge to remove just that edge. No map handy? Skip the upload — it works on a blank board too.