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.

Mixing a batch.

A little 5 on 1.

distributing free literature

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.

Try Neo Scavenger if you like things like Zomboid

if they are still active the mmo's champions online and star trek online are tab targeting and even allow for some scripting. I actually had posted on reddit that I would like for people with disabilities to know about them. the right builds can be done with input every so often that does not need to be split second (some roles do require a bit more timing but if its just one handed its toatlly doable)

Point and click visual novels. Or JPRGs.

The android port of Star Wars: Knights of the Old Republic 2 is amazing! Id recommend turning on all the pause options, it effectively turns it into turn based combat. The gui is incredibly intuitive, and you can perform all of your actions either with a stylus or even a single finger. If you like star wars or dnd, its basically guaranteed to be a fun game. Do note though that you will want to install the Restored Content mod, which will require either a rooted android or a computer to allow you to install the mod. It fixes a massive amount of potentially game breaking bugs and restores a bunch of cut content. Not sure what happened with the development of the game, but im guessing the studio forced it to be released before it was complete.

Vampire Survivors

Geometry dash only requires a single finger.

Gooning can be done one handed. If you need to use the other hand, stick with an index or middle finger.

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

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/

https://gisnep.com/doomscroll/

Have you considered pocket ball?

Obligatory Dwarf Fortress

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

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.

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.

Balatro and Into The Breach

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.

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.

Citizen sleeper! Card games also work

Fucking hell, are you okay?

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

Turn-based?

Cities Skylines 2, and www.openfront.io

Fruit Ninja comes to mind.

Rhythm Doctor

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.