Word Ladder

Word Ladder is the old pencil-and-paper puzzle given a tree to climb. COLD becomes CORD, CORD becomes CARD, CARD becomes WARD, and WARD becomes WARM: one letter changes each time and every step along the way has to be a word somebody would actually use. Here the ladder is a real one, roped to the trunk of an oak in the late afternoon, and each word you place is a plank with the letters burned into it. A squirrel hops up to the new rung as it lands, leaves come loose, and the treehouse door at the top swings open when you finally reach it.

Every ladder has a par: the shortest route there is, worked out before you start. Match it for three stars, take one rung more for two, two more for one. When you are stuck, a leaf will show you which letter to change next, and you can always take the top plank off and try a different way. Longer ladders climb into the evening, when the light goes amber and the first fireflies come out among the branches.

There is a Daily Ladder that is the same for everyone on the date and keeps a run of days; Climb, where the ladders get longer and longer until three of them beat you; Practice in three sizes, from three-letter words up to five; and Race, which asks how many ladders you can finish in ninety seconds. The word list was written for this game: over four thousand everyday words, and the puzzle is built by walking the map of which words are one letter apart, so no ladder is ever impossible and none of them is a dead end. Type on a keyboard or tap the wooden keys; your streak and your best runs are kept in your browser and nowhere else.