I don't spend as much time on crossword puzzles as I used to do when riding the trains to work, but I like that Spelling Bee puzzle in the NYT online - they give you seven letters with one being required and you make as many words as you can think of. Answers go up the next day so you can roll eyes at what you missed. It's good for a coffee break. Annoying sometimes when you find a word they seem to have omitted for no good reason.
Sudoku is fun, I keep an app on my laptop, it's my go-to when landing in a hold queue on the phone.
And I like the free jigsaw puzzle of the online New Yorker. Three levels of complexity and it just makes a puzzle out of a randomly chosen back issue. Another fun coffee break kinda thing.
Jigsaw | The New Yorker
www.newyorker.com
On that one (and because I'm a subscriber) then after I complete the puzzle I sometimes log into the archives and prowl around that issue date for some articles, stories or cartoons.
I play Wordscapes on my iPhone. It is similar to this. However, it is sometimes difficult for the "spelling challenged."