Such a game: we change one letter in a word to get another word.
You can also add or remove one letter.
Dallas
Pallas
Peter Simon Pallas (https://en.wikipedia.org/wiki/Peter_Simon_Pallas)
allay
QuoteThe verb allay is used when you want to make something better or eliminate fears and concerns.
calla
QuoteSouth African plant widely cultivated for its showy pure white spathe and yellow spadix