Asklemmy

Do lots of drugs

Put an alarm and sleep.

Talk to people? Does the airplane have a bar? Even if you don't drink there's probably people there willing to have some conversations.

If you can get an emulator on your phone you can play old games. Nealy endless hours of fun to be had. I recommend lemuroid and Legend of Zelda A Link to the Past.

Depending on the airport/country you are stuck in, you can take a trip to the nearby city. I was once stuck in Singapore Airport for 13 hours and just took a day trip to Singapore. It's a bit risky in your scenario because they might move your flight forward but depending on the circumstances of the delay it might be fine.

Almost all airports have a spa or some kind of wellness offers. Would be a great time to try it out. Maybe you discover something new you like, worst case scenario you wasted 1-2 hours. In general look up entertainment offers at the airport. Most have at least an internet cafe that would allow you to play "proper" games since mobile games aren't yours.

This is the perfect moment to write a short story

Start a new factorio game on a handheld device. Don't forget to get out of the plane after 20 hours.

Or watch the extended cuts of Lord of the Rings plus The Hobbit. That is 1171 minutes (=20 hours).

On a more serious note: I would schedule multi-hour blocks of work time, off time and sleep. Watching movies and playing games is much more fun after work is finished, and you feel like you accomplished something. It's also a good opportunity to do the tedious things you always wanted to do but never had the time and/or motivation (finances, taxes, studying, sorting files, sorting mails, that kind of stuff). It's not like you had anything better to do or other places to be, and it might actually make you feel better. After three hours of working you will look forward to the movie, before going to sleep.

Baba is You. It is one of the best puzzle games ever made, and available on mobile.

I rarely play mobile games, but here's one that I quite like when I need to kill time or be active while media is in the background: Auralux 2.

I initially thought that the game wasn't properly weighted for difficulty, but then found that I just needed to adapt my strategy. I can complete most levels in 2-3 minutes, though some might take 4-7 depending on how it breaks (I play on the fastest setting after getting good at it on normal speed).

I pick it up when my partner pauses to get a snack, go to the bathroom, or take an important call. I can set it down as soon as she's ready because there's no real stakes; I'm really just competing with myself to score faster and faster "best" times. I also play it while listening to podcasts if I can't be physically active (or when I'm lazy).

I play on iOS. Not sure if it's on Android.

Sleep, eat, sleep, watch/hear/read something, talk to random people (preferably other stranded people), visit the smoking lounge, walk though all the stores, maybe buy a magazine.

And all the people recommending mobile games... I've wasted hours on end playing tower defense games, bridge builder or something like that. Get up inbetween and mix things up. Everything will get boring in that situation.

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

ETA a much better performance.

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.

In case you get stuck again and need more games:

• DevilutionX (free, open source, needs gamedata) lets you play Diablo1 on Android, very good time killer (you might need to fetch the gamedata somewhere)
• Out There: Omega (paid but one time purchase) is a relaxed starship roguelite
• Battle For Wesnoth (free, open source) fantasy style tactical game
• Jagged Alliance 2 Stracciatella (free, open source, needs gamedata) - Jagged Alliance 2 on Android, tactical RPG, great timekiller like classic UFO or the old Fallout games.

Notable mentions: WorldOfGoo, Human Resource Machine

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

Go exploring. Walk the airport and go to other wings if it's a large airport. You might be able to find a luggage locker so you can walk without carrying anything.

In the same line, there are a lot of games that gamify walking. One. Two. The goal here is to exhaust your body a bit better for the 13 hr flight.

Learn something. A new language, maybe. A skill. Learn braille and go around the airport decoding the braille signs.

Do an airport scavenger hunt. Can you find yarn and maybe practice finger knitting? Maybe a deck of cards and learn some card tricks?

Talk to people. Honestly I'm an introvert so I rarely do this but it can be fun.

Anything interesting like a museum in the area around the airport? I had an 8 hour layover once and I just left the airport and went to a nearby Air Force museum of some sort. It was nice to walk around instead of just sitting in the airport, and I got to see a B-24

Turn off your phone.

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.

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.

Maybe learn how to play chess?

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

If you're into metal/hardcore/etc at all, you should watch the documentaries Parkway Drive (Post-hardcore/metalcore band from Australia) has made, extraordinary stuff. This is the first one.

I also recommend chess.

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

Vampire survivors and random lore vids.

Watch MentourPilot on Youtube since you are gonna be on a plane, it fits the theme.

First, watch this: https://youtu.be/ePDl1JNqjpM and learn how to land a plane in case of crew incapcitation. Now you can just daydream about becoming a hero that saves the day!

But um... safety tips... Make sure you count the rows to the nearest exit, if there's a crash landing in water, please do not inflate your life jacket until you left the plane.

Then, watch all those plane incident/accident videos (https://youtube.com/playlist?list=PLiNyr6QSO28P2bKMcv2O_lK83jsR0A9-W) on MentourPilot so you can be thinking about your demise, the meaning of life, etc... for the entire flight and not have time to be bored.

(But seriously tho, MentourPilot's series of incident/accidents videos is very entertaining and informative)