Long ago there was a publication, edited, I'm pretty sure, by Will Shortz, called the "Four-Star Puzzler." (It was affiliated with Games magazine, whose highest ranking of difficulty for a puzzle was three stars.) They ran a crossword called "Element 18," (argon) wherein all the Rs that would normally have been in the answers were simply left out. In this puzzle, instead, we are forced to add Rs to what would be sensible answers to the given clues, which results in random new words. Hmph. Not my favorite.
We actually "finished" this puzzle with blank squares, then slowly realized that Rs would fit into all of them, including, importantly, 63A: Moderates (E_ASE_S), and then the resulting word, if parsed into two parts, would read "Erase Rs." But to have the puzzle accepted by the software, we needed to do exactly the opposite.