I love sudoku, but not online. I bought 3 books called "Pocket Posh Sudoku" from Barnes & Nobles. They are smaller books and I take one with me often. Anytime I am waiting for something, I open it and begin a puzzle.
I do play Freecell on the computer. Almost every game is winnable. I have not encountered any that aren't, but there are supposed to be a couple of possibilities that you cannot win.
One of my friends loves Kingdom Hearts (she plays it on her phone.) I also had Candy Crush on my old phone, haven't re-downloaded it, but that is good for killing time.
Watching TED talks on Youtube... (usually one of the talks will get me interested in something I ran down that rabbit hole)
Check out "Wait, but why" -
https://waitbutwhy.com/
Or "This is why I'm broke" -
https://www.thisiswhyimbroke.com/
Board games are fun, but you need people to play. Quelf (make the rule no pics or videos are allowed!) is a LOT of fun. Apples to Apples (I have the Big Bang Theory party game, which is very similar). 3 or 4 person chess (I do not have the 3 person one, but I do have the 4 person version... there are gaps in the rules for that one.)
