Asklemmy

The best advice of keeping moving has already been suggested, but buy a real book, and maybe a crossword or other such like. Avoid technology.

Sonic 1, 2, and CD have been ported to Android.

Get a pack of cards and learn some fake shuffles (via YT) then memorize the 673 King Street trick.

ETA a much better performance.

Try Dumb Ways to Climb. It's free without ads.

Buy books? 20 hours man, I could burn through at least two.

Uhh, start drinking?

Maybe learn how to play chess?

For games, my suggestion is that you try a whole bunch of them; get Google Play Pass and, if you have a Netflix subscription, browse through the list of Neflix Games and try anything that looks remotely appealing. None of these are gambling or freemium - they have no way to make money from you except for your continued subscription - and there's something for pretty much every conceivable genre.

If you can give any guidance about the specific sorts of things you like from games (action, story, puzzles, building stuff) I'm sure people can recommend some specific titles.

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

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.

I know you mentioned audiobooks but what about some digital books? Personally, reading makes my eyes tired so I know that, for me, reading something would be a good way to provoke a nap.

As a response to the idea that you may get fatigued by passive media, a book may be a good balance to that. With movies, shows, and audiobooks, you're going to be listening the whole time. It's just constant noise. A book may be more meditative.

Which reminds me, this may be a good time to practice meditation.

I wouldn't get wasted, if you're in your 30s that can give your worst headache ever. If the wifi is good enough, maybe start a series? Possibly something with short episodes, a well-selected anime will easily kill something like 10 hours. And if possible, try to get as much sleep as possible

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.

you can't kill an idea

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

There are very good mobile games without subscriptions, virtual coins, loot boxes and shit. Some examples on iOS:

• Sawblades
• Ollies Arcade
• Knotwords
• High Rise

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.

Twist your thumbs

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

Vampire survivors and random lore vids.

The most addictive and a complete experience in your pocket kind of game is Crashlands. It's amazing if you're into games where you have to craft things to survive. Definitely recommend giving it a try.

Play some chess on chess.com

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.