Not sure what sort of length on play you’re looking for but wingspan and terraforming Mars are both really good board games that have good-to-quite-good mobile versions.

Cell to Singularity is a great little mobile game that does have microtransactions but are easy to ignore/avoid. I played through it several times and may need to dust it off for another playthrough. Great music too.

Old school RuneScape, it has free “demo” version which you can easily put a 100+ hours in. And if you really love there is a subscription model that’s kinda expensive if you bill monthly, but no other micro transactions.

Monument Valley and Gorogoa are both excellent and free of nonsense.

Both are available on mobile and Steam. Gorogoa also on GOG currently 70% off.

Meant to link monument valley 2: https://www.monumentvalleygame.com/mv2

Pixel dungeon, but it’s not really low stress.

Wuthering Waves is Hella good. Technically it’s an open world gacha game, but I played through all the storyline (the developers will be forever updating the story a la Genshin Impact), and I never spent a dime on it.

Also, I have spent money on Cooking Diary. However, I went about 3 months of daily play before I did, and it was more about me being impatient/telling myself “You got 3 months of daily play, you can drop the devs $4.99”. I’ve played that game just about daily since Memorial Day 2023, and I’ve dropped $5.00 quarterly. There are regularly moments of infinite lives that exceed an hour or two, that it genuinely isn’t necessary. I spend the money more as a “thanks for not making this ducking game contingent on microtransactions, making it good, and maintaining/update it.”

2048. Though im sure that one has ads. Probably depends on what you grab from the internet, as usual.

Mobile games suck.

Any of the PAID games from Kairosoft. Dungeon Village, Grand Prix Story, Game Dev Story. He has since re-released all his games as f2p microtransaction junk, but the full price versions are generally really good.

slay the spire has a mobile port

Try searching on https://www.darkpattern.games It seems like a vast collection with reviews aimed at finding and naming healthy and unhealthy games

There are a lot of great suggestions here already, so I will just share Mini Review with you as a discovery tool. I like to use them because they have a lot of filters to help you find a mobile game. For example, here’s their list for free, single-player, offline games with no ads or in app purchases, sorted by highest user score. They also have an app for both Android and iOS with the same info and filtering as the site.

Some good games I recommend are Alto’s Adventure / Odyssey, any bejeweled game, Cell to Singularity, Idle Slayer, Monument Valley, Reigns, Sky Force Reloaded, and Stick Fight Shadow Warrior. Hopefully that’s enough!

I really like Usagi Shima. There is not much gameplay, but it’s a nice game to just relax for a few minutes. Also “Really Bad Chess” is a nice twist on chess. :D

My recommendation l is going back to the basics: chess, especially lichess.org

You can choose a mode however you want, and it may or may not be stressful. Multiplayer with friends or random online people, choose a time between 30 seconds for a game and infinity to move.

If you don’t want to play right now, you can solve tactical exercises.

Word Cookies. I absolutely love it. You can pay for things, but it is absolutely not necessary and is basically only if you feel the need to use boosts that allow you to cheat your way past the level. I think it costs $2 to go ad-free.

It does give you regular popups asking if you want to buy coins, which I admit is annoying, but they are unnecessary to enjoy the game. There’s also endless opportunities to get coins and other boosts for free. I have something like 80,000 coins and dozens of boosts and other than the $2 to go ad-free, I’ve never given them any money.

You do have to have certain word skills to enjoy it as much as I do. If you’re the sort who can crush it at Boggle, it’s the game for you.