Rungs

Turn the top word into the bottom word, one letter at a time. You can use two more steps than the shortest solution needs.

• -Turn the top word into the bottom word, changing one letter at a time.
• -Every step has to be a real five-letter word, and only one letter may change: the other four stay where they are.
• -Each word you add is a step. You can use two more steps than the shortest solution needs. Run out before you reach the bottom word and the puzzle is lost.
• -A word the list does not have is refused on the spot and costs you nothing. Only a word that is accepted uses a step.
• -An undo takes the last step off the ladder and gives it back to you, so a step you undo is not counted and never reaches your result. You get three of them.
• -Any ladder that reaches the bottom word within the step limit wins. It does not have to match the shortest solution.
• -No hints. Both words are on the board from the first second.

Where to start

Read the bottom word before you touch the top one, and count the letters that already agree: those are the ones you are keeping, and every other position has to change at least once. Work from whichever end has the fewer ways out. A word like STORK has two or three neighbours and CHASE has a dozen, so starting at the sparse end means fewer branches to be wrong about, and the middle is where the two halves meet. Trying a word costs nothing if it is not in the list, so guess freely: the only thing a rung buys is a word that was accepted, and the only way to waste one is to accept a word that leads nowhere. When a branch dries up, undo rather than spending your spare rungs climbing back by hand.