Asklemmy

Mini Reviews is an android app that has robust filtering features for games. You can download offline games so you don't have to worry about spotty connection. Pocket City 2 is pretty fun and a good time sink, only costs $5. You could also play a text based "choose your own adventure" type game. If.youre artistic, I'm sure you could find a paper and pen to doodle on as well. Maybe a take couple of hours to feel the gravity of your own mortality. A little existential dread never hurt anyone

It may sound stupid, but try learning some card tricks or play solitaire with some playing cards?

Buy a pack of sticky notes and a pen and let your imagination go. Write weird facts and trivia, or just whatever you want and stick 'em in places where people are gonna look, like on maps, mirrors, napkin holders at the bar...
Then just wait and watch

No advice, but I sympathize. I once sat listening to music while waiting for my flight to board. When there was no activity and fewer passengers in the area than I expected, I discovered that while I had been waiting they changed the gate for my flight. I ended up waiting in Chicago Midway (this was before their big upgrades in the early 00s) for 12 hours. It was hell.

You could watch The Terminal 9 times back to back, and have just enough time left to be disappointed by some overpriced meal at the Wolfgang Puck.

Try Monument Valley it's a one time pay puzzle game that moves like an MC Escher sketch.

I would say get a hotel room, but it has uh, been 6 hours since you posted this so…

I highly recommend emulating games on your phone. Some of them aren't great without a controller but its worth a shot.

Puzzle books? I like to play with variety puzzle books, commonly sold near magazines :3 Crosswords (and varieties thereof), word searches (+varieties), crypto puzzles of various sorts, number puzzles of various sorts, the funky neat ones where some of the words share some letters (like, a letter fills a vertical region to be shared by one or more words), uhhh... oh also I like to write the solutions in Thorass :D https://forgottenrealms.fandom.com/wiki/Thorass_alphabet Though the numerals are garbage. D'ni numerals are far, far better 👍

Also, I daydream for hours at a time. ... But probably you don't or else you wouldn't be asking for ideas I guess 😅

It's a damn shame that you can't go to a pharmacy in the airport, tell this tale, and get some xanex to zonk out and time travel to your destination.

The Lahey link made me laugh way to hard, I've been sick as fuck the last 2 days and I'm laying on the couch watching trailer Park boys with a decent buzz so it's fitting.

Have a 2 hour phone chat (with spouse?)

Buy a note book and write a diary to remind yourself of everything that has happened in the last year.

Vampire survivors and random lore vids.

It's not gonna last you 20 hours, but last I checked the official Sonic 1, 2 and CD ports are all free on mobile (and they're really good).

Do you like Roguelikes? Slay the Spire is really good and it's on Mobile.
It's a port from PC, so no microtransactions or garbage like that, one purchase and done.
There's also Mindustry. It's a mix between Tower Defense and Factory game. This one also has no MTX since it is a Open Source game. Free on Android, 2 Bucks on iOS.

As for android games, if you're into tower defense, give infinitode a try :)

Twist your thumbs

If its your thing try kearning a language on Duolingo or something like that

Unsure of your preferences with games, but Shattered Pixel Dungeon is free, offline, no ads, and the only purchases are for aesthetics to support the app. It's an 8-bit rogue like, and never the same game twice.