Shattered Pixel Dungeon is great, it's an open-source dungeon crawler. Neither adds, nor transactions, micro or otherwise. If you want to pay tho, there's a donation link for the dev team.

And if you still want too play GBA games, check check out the Lemuroid emulator, it's also open source and has no adds. Works for nintendoDS too.

You can find both of these on F-Droid. They're also be on Google Play, but since I've only tried the F-Droid version idk if the other has adds.

Started playing Balatro on my phone at work.

Surprised Slice & Dice hasn't been mentioned, it's amazing. That and Dawncaster.

A useful tool is DarkPattern.games, which lists dark patterns in mobile games (such as micro transactions).

• Slice & Dice
• Balatro
• Stardew Valley
• Terraria
• BloonsTD6
• Arcadium
• Shattered Pixel Dungeon
• Geometry Dash
• Mini Metro
• Brotato
• Slay the Spire
• Peglin

Whatever emulator you can run and the ROMs of your choice.

Mindustry is basically Factorio-meets-tower-defense. It's open-source, also available on desktop.

Slay The Spire

Mini Metro. Its a transportation strategy game where you build and manage a city´s metro system through the style of the London tube map. You pay once and get the whole game. No ads or micro transactions.

Open Tyrian is an old shoot em up thats open source and has been ported to dozens of platforms, including android. It plays very well with touch controls.

If you want a Minecraft like game thats free and has no microtransactions I recommend Minetest (Now called Luanti). Its open source and has tons of mods.

Into The Breach

Some good ones from the fdroid app-repo.

Shattered Pixel Dungeon - already mentioned roguelike

SGT-Puzzles - already mentioned microgame puzzlers

Frozen Bubble - already mentioned bubble-shooter

Vector Pinball - already mentioned pinball

https://f-droid.org/en/packages/net.artificialworlds.boxstacker/index.html - Physics puzzler

https://f-droid.org/packages/com.simondalvai.ball2box/ - flick ball to the box for 3-stars

https://f-droid.org/packages/com.gpl.rpg.AndorsTrail/ - Massive story quest driven RPG

https://f-droid.org/packages/de.chadenas.cpudefense/ - Tower defense on a PCB

https://f-droid.org/packages/ch.logixisland.anuto/ - trad tower-defense

https://f-droid.org/packages/it.alessandropira.wesnoth114/ - hex turn-based fantasy RPG

https://f-droid.org/en/packages/org.lettucepie.flickybee/index.html - flick the bee through the course

I didn't see Unciv recommended yet, it's a decent mobile open source version of Civilization.

Pocket City 2 also gets a shout-out, it's not very deep but a nice casual city builder with a one time purchase.

Slay the Spire is one of my favorite games of all time, and has a nice android port I play before bed all the time. No ads, just caw caaaw

Balatro and Slay the Spire both have a lot of reply value. Very different games.

Shattered Pixel Dungeon is a really good roguelike for mobile. Ton of variety, no ads, only thing you can buy is a supporter pack that gives the ui a different fringe color, and that doesn't get pushed.

Papers Please

Rollercoaster Tycoon Classic, if you feel like playing rollercoaster tycoon 1/2 on your phone. They slightly altered the UI to make it more touch friendly.

Stardew Valley! It was worth the $5 already in vanilla, then it got updated with more content at no extra charge and then again. And now 1.6 is around the corner with even more. It is the love child of one dev that keeps on giving and giving and giving. And there are tons of mods of all kinds including entire world overhauls that adds even more replayability. Very much recommended.

Plague Inc - control a plague and try to kill all humans on earth (tactical simulation)

Interstellar Pilot and Interstellar Pilot 2 - human explorers jumped through a wormhole to distant space and lost contact with earth. Factions control different sectors, some are friendly some are warring. You start with a single ship and try to do anything between simple survival and building a new faction to conquer all of this new space. (Open world rpg with tactical simulation elements)

Battlecruisers - The machines won, humanity is no more. You are not the smartest robot and somehow you managed to accidentally hijack a military battlecruiser. You are pursued across the world's oceans by several navies while you try to figure out how to get out of the mess you created. (shipbuilder)

~~Freeciv~~ Unciv on Android is an almost feature complete re-creation of Civilization 5 with minimal graphics. You can also download the JAR and run it on a desktop if you have a Java SDK installed. As a Civ player that started with 4, I found it easier to pick up than freeciv which is trying to replicate something more like Civ2.

Edit: provide correct name

Https://lichess.org/training lets me pretend I'm improving my mind by playing.

The Netflix version of mobile games have their micro transactions removed (or at least all the ones I've downloaded).

Balatro

Threes

Fun puzzle game that got ripped off by 2048 and it's endless clones. They wrote a blog post on how shitty mobile game development can be.

Puzzles

Bunch of puzzle games with no ads or transactions

DATA WING is a great racing game with an amazing, short story.

Turnip Boy Commits Tax Evasion is a fun little RPG with lots of humour

Dribble is a surprisingly unique platformer, free with no iaps and unique swipe controls.

You can get ports of the marble blast games on Android, I particularly like Ultra.

You can play Morrowind on Android through OpenMW Android. I think this is the most updated version but you have to build it yourself: https://gitlab.com/cavebros/openmw-android

Endless Sky is a solid space trader and combat game, free on f-droid

Frozen Bubble is a pretty fun ~~bubble bobble~~ Puzzle Bobble clone, also on f-droid

Arx Libertatis allows you to play the full version of Arx Fatalis, a super in depth underground RPG inspired by Ultima Underworld. You need the PC game files to transfer to your phone though.

Balatro, works really well with touch, numbers go brrrrrrrrr

I grabbed Rusted Warfare RTS not long ago. It's a real-time strategy game. $1.99 on the Google Play store.

Minecraft pocket edition has microtransactions but it only ever pushes them on the menu never actually in game so maybe that's a compromise? Also it's simple but this port of Simon Tatham's portable puzzle collection is pretty good and has no ads or microtransactions https://f-droid.org/en/packages/name.boyle.chris.sgtpuzzles/

If you enjoy puzzle games then Baba is You, Snake Bird and Railbound will keep you busy for quite a while.

Balatro has no micro transactions but will consume your life regardless

The best Windows game ever made, ported to Android

The whole Cube Escape Series.

I really enjoyed playing the platforms cats are liquid: a better place(there is also a light in the shadow, but that game is worse); catbird, nameless cat, kitty death room and the 4 dadish games

If you want a game that has microtransactions, but rarely try to sell you things, i would recommended the tower defense game(i think) the battle cats. There is also a 10 year celebration that gives you a lot of rewards