Depending on what you'd want to emulate, emulators can be very efficient on low-end hardware (i.e. gpSP for GBA).

Infinite fun:

• https://f-droid.org/en/packages/name.boyle.chris.sgtpuzzles/
• https://f-droid.org/en/packages/com.shatteredpixel.shatteredpixeldungeon/

This isn’t related to the question, but:

Excuse me, is that the promotional art for Total Overdose, a game I had only assumed had been lost to time and everyone forgot existed (not that it was good)?

While not free, I can recommend both Slay the Spire and Balatro as ideal mobile games. You won't regret it if you manage to find the spare cash

These are the best I've found that also have no trackers in them (most are in f-droid, a couple from aurora/playstore):

• shattered pixel dungeon (roguelike)
• breakout 71
• endless sky (space trader)
• pewpew live (stick shooter)
• vroomies (odd swipe racer)
• Datawing (super fun racer/timetrial drifting game, best out of all of them IMO. Not on f-droid)
• the frostrune (point and click adventure)
• ScummVM (emulator for classic point and click games, many of which are free)
• Arx Libertatis (an engine to run Arx Fatalis, though you need the OG game files, which isn't free, but... Yarr)

I think Star Wars Kotor and Kotor 2 have android ports. Those are great RPG's, but not free.

Three that I like to play when commuting

Breakout 71 https://f-droid.org/en/packages/me.lecaro.breakout/ - This one is great though all the powerups make it a bit too easy if you play it for a while. But it's a good one if you just want get into playing something quickly.

Ball2Box https://f-droid.org/en/packages/com.simondalvai.ball2box/ - It's a pretty simple game but surprisingly addictive if you're like me trying to get a perfect score on each level (there's a ton of levels).

Calculate https://f-droid.org/en/packages/com.rechnen.app/ - Practice doing math in your head!

I've really been enjoying Slice and Dice. A rpg dungeon crawler where your party and enemies abilities are represented by 6 sided dice. Each face has an attack, defense or debuff ability. You can collect items and level up your characters through the dungeon. The more you play the more classes, items enemies and game modes you unlock.

The game state saves when you close your phone or leave the app and there's enough rng that gameplay doesn't get stale. You can play it with your phone in vertical or horizontal orientation and with only your thumb so your other hand is free

Awesome text based mystery horror puzzle game, works in browser

https://william-rous.itch.io/type-help

Can also search through MiniReview. It has a robust filtering system including monetization type, network connectivity, and sub genres that is way better than any other way I've seen to find games on your own

Any picross game. Don’t have android so I don’t have anything specific to recommend, but it was my goto time killer before switching to books.

Try games from yiotro, particularly Antiyoy - great strategy/puzzle games, even if graphically modest. Card Crawl is also pretty good if you like a quick card game. If you want foss, Gauguin is a cool sudoku-like on fdroid.

Magic Survival. It was the inspiration for Vampire Survivors, a fantastic game in its own right. You can lose so much time to these games.

Offline Games from JindoBlu.

A variety of timewasters with more added pretty regularly.

How dare you use Total Overdose with that title :(

Nonograms Katana, I just love nonograms and there's even more around that

if you get scummvm and dig up some downloads, the backyard sports series (until football 2002, which itself is buggy on scummvm) is very fun

you can also buy them officially if you so choose

I ended up installing some not-low-end gacha games, and felt pretty impressed at how well they could run and even have some moderate combat complexity for how shitty touch controls are.

Zenless Zone Zero, for instance, has a lot of the combat built into dodge timing/character swapping, and little work put into movement and camera controls.

https://nobsgames.stavros.io/android/?name=&genre=&rating__gt=&price=free

You might find something interesting here.

Arcaea is quite a good rhythm game that should run on lower end devices. There are song packs, but there's enough songs in the free base version.

Man I love games practically more than anything but you don't need to be plugged in all the time. Reading a fantastic book is a way more fulfilling use of your time on transit compared to playing a shitty mobile game.