Does anyone here know a website or app with a collection of Japanese word puzzles (like for example the collection of word games at Games | The New York Times Company)?
I have used the wordle variant at Kotobade Asobou 言葉で遊ぼう and know ‘J-crosswords by renshuu’, but the latter are not really crosswords as the words are only loosely connected by one or two mora.
I’ve been doing a Nikoli crossword book in a thread on these very forums off-and-on for the last seven years or thereabouts if that counts as a website or app. 
I also downloaded a couple of free crossword apps to my phone - one by MokoSoft and one by, uh… dicwizard, both just called クロスワード - but I don’t know good they are on the grand scheme of things, they’re just the ones that happened to catch my eye first.