Point and click visual novels. Or JPRGs.

Pokémon Let’s Go [Eevee / Pikachu] can be played with a single joycon vertical in one hand. They designed it to be played with their Pokéball controller, accidentally making it super accessible.

You can probably play Vampire Survivors. All you really do is move around.

If you can still use a mouse well, grand strategy games can be played with one hand. Despite all the (deserved) criticism they get, paradox games are a lot of fun. (and their modern ones even feel like a full game without having to buy any dlc) They can be a bit difficult to keep up with without a keyboard though so play on lower speeds.

If you are more concious about who you give your money to, endless legend 2 is a 4x published by hooded horse that is very good (think civ but fantasy) and since it is turn based it is a lot easier to play with just a mouse.

Geometry dash only requires a single finger.

Dwarf fortress, chess, crosswords, Nonograms, sudoku

Check out scummVM and ROMs for old point and click adventure games like grim fandango, monkey island, Sam & max, etc

I hear pocket pool is a lot of fun.

Try Neo Scavenger if you like things like Zomboid

Cities Skylines 2, and www.openfront.io

Which thumb? If your left thumb is still functional, when I had a hand injury in middle school, I got to be really good at Super Monkey Ball 1 and 2. If your dominant/mouse hand is still functional, anything mouse-driven ought to do, and that covers a wide range of genres from CRPGs to adventure games to 4X games and more.

Turn-based?

https://gisnep.com/doomscroll/

Might not be in your library, but mouse only game I've been enjoying is beat cop.

80s love letter to cop games, in the style of papers please. Reviews are a little mixed, it is a particular game, and it's 80s warts and all. On sale currently.

https://store.steampowered.com/app/461950/Beat_Cop/

Have you considered vampire survivors? That’s a fun one on iOS and android.

Have you considered pocket ball?

Does this actually get in the way when you're playing with mouse and keyboard? I do use my non-dominant thumb for hitting the space, alt and strg keys, but in many games that's kinda optional, especially when the games aren't super challenging. Turn-based RPGs like Divinity: Original Sin or Baldur's Gate 3 should work great.

Monument Valley 1, 2, and 3 (mobile games). An interesting set of puzzle games with good visuals. They only require single taps to work.

Also can get a mouse for the Steam Deck (or a PC if you have one). There are a lot of good games that you can likely use with a mouse if the hand/wrist motion doesn't cause pain or discomfort for your thumb.

Balatro and Into The Breach

Any points and click adventure game, there are loads including old classics and modern good games.

Monkey Island remasters are fun and can be played with mouse. Broken Sword games are also good.

Rusty Lake games are great if you prefer more puzzle games than narrative ones. Still has a great somewhat surreal plot just not like a point and click narrative game.

Also If you havent played dwarf fortress now is the time to learn, the siege update came out this week. Mouse or keyboard, or both, but definitely can be done one handed.

Vampire Survivor that others have suggested is a good shout, one hand on the keyboard is enough and its very addictive.

Obligatory Dwarf Fortress

Fucking hell, are you okay?

Edit: Also Syberia is a good game. It's point and click.

Fruit Ninja comes to mind.

Citizen sleeper! Card games also work

Rhythm Doctor

Shogun Showdown. Into the Breach. Cobalt Core. Path of Achra.

Have never thought about it so dunno how awkward it'd be, but maybe NES and SNES turn-based RPGs? Quite like Mystic Quest out of them, Final Fantasy on easy mode pretty much but pretty chill and enjoyable imo.

Would recommend also hasicontent, Slipways Classic and Dust Bunny, all for PICO-8 and on Itchio, and those I think that'd be more feasible one-handed. Also Final Fantasy II for the PSP specifically as it's the most feature complete version, and this one iirc is feasible with one hand.

Also more feasible and native to Android if that's your phone system, Chloe Playtime (Google Play), Codemancer (Itchio), Deeper Down Dungeons (Google Play), Quest of Dungeons (Google Play, Humble Bundle, Itchio), REDDEN (dunno if still distributed anywhere) and Tyrant's Blessing (Google Play).

And don't remember any, but if there's any game compatible, maybe also check stuff playable on ScummVM, Joiplay, and other similar projects?

Anyways, hope you get well soon, fellow stranger!

Shapez or shapez 2 are really good factory games that dont really require a lot of thumb movement, else play the west of loathing, this one is fantastic turn styled rpg rame where you go west after the cows came home, also there is a spittoon, you can reach into it, and have the narrator describe the horrors you feel whilst poking around in there to fish out a assortment of spit infused garbage to wear on your person

Turn based RPGs would be good. You could use the controller one handed. Especially things made for game boy, since there aren’t a lot of buttons.

WHY YOU NO WANT PORK BUN??