When you’re stuck in an airport during a long layover, sometimes a light browser game can save the day. The best ones load fast, work even with weak Wi-Fi, and don’t drain your battery too much.
I usually go for simple memory games, word puzzles, or small idle games that don’t need constant attention. Minimalist platformers are also fun, and even basic doodle apps can help pass the time.
What about you? Do you have favorite browser games you turn to when waiting for a flight?
The best browser games are the ones that keep spammers at bay.
Now I really, really feel ancient!
When I am stuck at an airport I read a book! 
Guess I was born in the wrong century! 
I can't play games for too long at a time. And I have a set of solitaire games on my phone which don't really need wi-fi. But I'm with karazyal - waiting for a plane, I have books loaded on my kindle - I would rather read an actual book, but books are heavier and bulkier. If I am not traveling with someone who needs conversation, I can finish a trashy romance in the time I am at the airport or on the airplane.
If you want something light but still a bit strategic, try Trimps or Cookie Clicker, both idle browser games that run fine even with sketchy Wi-Fi. For puzzles, Crosswordle and Semantle are great if you like word challenges but want more variety than Wordle. I usually just keep a few bookmarked in case I get stuck on a layover.
When I have a long layover heading overseas, besides reading a book, I notify my hotel by email and tell them I will be arriving later than my original schedule. This way they will not think I am a "no-show" and give my room away.