Word Ways readers are familiar with Lewis Carroll's word ladders. As a variation, Dave Morice suggested in the August 1989 Kicksaws a game which he called Stepladders. Two words join only if the letters which are exchanged are adjacent to each other in the alphabet.
Gordon, Leonard J.
Word Ways: Vol. 25
, Article 5.
Available at: http://digitalcommons.butler.edu/wordways/vol25/iss1/5