Late to the party as usual, I've just discovered these. They're similar to regular crosswords, but the clues are devilishly convoluted within certain rules. Clues are bifurcated: one part is a straightforward definition and the second part may be an anagram, a hidden word, or a homophone, for example. There are even clues within the clues to indicate which kind of wordplay is involved.
For example, the clue for "booze" may be "Expresses displeasure with liquor, we hear." The word hear indicates a homophone. Expresses displeasure=boos. Boos sounds like booze, a word for liquor. Good exercise for your brain if you like word puzzles.