I like 2048 and 7 Words. I think I may try Word Brain, and I’ve been meaning to get Tetris.
Bubble bust-faster and more fun than Bubble Shooter. I can’t stop playing. They have a new version called Bubble Bust Popping Planets, but I get ads every so often. I still play it, though.
My kids got me hooked on Flow Free
Pac-man doesn’t need network.
Dots Two, way more entertaining than Dots - it was featured in a Time magazine article. There are lots of free games on my Kindle Fire which are entertaining up to a point, including Sims FreePlay, SimCity BuildIt, and Paradise Island 2 (I like cities and islands). Disney Frozen Free Fall turned out to be entertaining mindless fun. If you like hidden objects, Midnight Castle is fun.
Euchre is fun, no data and mindless. There are quite a few free versions. You can play a hand or an entire game (when one team gets to the score of 10 first). Different apps have different ways the players play. Actually, there is SOME strategy and a lot of luck. I just got hooked on it lately and find it fun.
Swipe Off
BubbleShell
BubbleWitch (I prefer the original version))
Unblock Me (a puzzle game)
Candy Crush Soda
Thanks for all the suggestions!!! Will be checking out the app store later. 
Flow Free is one of my faves. My daughter recommends Don’t Get Fired.
I really like bubble witch, too. Panda Pop is the same concept.
Hundreds
Polymer
Strata
Monument Valley
(I am partial to puzzles)
Old school suggestion - crossword puzzle. I used to have one in my purse when waiting in long line for hs teacher conference. Added bonus…some fun social time with other parents when DH and I were stuck for an answer.
tetris