Games

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.

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.

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.

Cosmic Combo, an iOS port of Johan Peitz’ PICO-8 game Cosmic Collapse, is good.

Gardenscapes is the original match 3 and build a mansion and is still my favorite. There are micro transactions to get additional power ups, but the fact that they are constantly updating with new seasonal events and you never run out of levels

Potion Permit is about $7, but pretty fun. If you got $10 to spare, Ex Astris is a jrpg that's pretty good.

Old School RuneScape potentially fits this description

Emulating a Nintendo DS and looking for stylus only games is my recommendation. Games like Kirby Canvas Curse, Kirby Mass Attack, and Warioware Touched are fun.

I played a cool one called Pirate solitaire, very charming

Emulation!

Out of the Dark is alright.

You can get a port of space cadet pinball from GitHub!

Walk master

Gubbins is a fun word game, it's a one time purchase and apparently part of the profits go to charity due to Hank Green investing in it in a creative way.

I play chess, mahjong on mobile.

There's also final fantasy pixel remasters, Baldurs Gate, planetscape torment, shadowrun games and trials of mana on mobile too.

Sparklite, I don't know what it looks like purchases-wise, it was free with gamepass and had no in-app purchases when acquired that way. It's probably one of the newest games I'll post about. New enough that it was possible to get it with gamepass, lol. The game sort of has a modern retro zelda feel. I don't think it's a particularly long game, but it's certainly enjoyable and pretty casual. I think if it has transactions, reading other reviews it might be like a "purchase the rest of the game" style thing. So basically a free demo that you can then choose if you like the game enough to pay.

Imagzle. There are "buy more levels" but there are plenty on the main one. It gives a picture, more or less, abstractly related to something. Art, movie, book, many random things

royal match has no ads at all, its pretty fun just gotta ignore the microtransactions which is pretty easy to do at least compared to other games

Antimatter Dimensions

Star command, anomaly, world of goo, EDGE, knight of pen and paper...

These are some good ones I got from humble bundle over the years but many are quite dated so not sure if they're still around. No BS microtranactions