From the webpage:
Welcome to the fantastic world of nerdy regex fun! Start playing by selecting one of the puzzle challenges below. There are a wide range of difficulties from beginner to expert.
From the “How to play” page:
Regex Crossword is a game similar to sudoku or the traditional crossword puzzle, where you must guess the correct letters in the horizontal and vertical lines of a grid. In Regex Crossword you are not given a word to guess, but a pattern that tells you which letters are allowed.
The NYT Crossword editors don’t need to start polishing their resumes. 😉
On the other hand, I can foresee office competitions!
Or at conferences? Someone needs to carry the word to the Balisage organizers