One Handed Games?

minion masters
its FREE

"The room" francise is nice

I see you've got Machinarium. I highly recommend playing that. It's a charming point & click adventure with excellent soundtrack and atmosphere.

lots of great game been listed, cant think of any to add
just wanted to wish you a speedy recovery and tell you Civilization was always there for me, one-handed or not
it keeps me busy and keep my mind off other stuff

I can totally relate =P
try also some Kongregate games, or on other Flash websites like Newgrounds, apart from the great Steam suggestions you had here!
go with point n click adventures, turn based games and so on.. =) and puzzles, easy and hard ones!
but most of all I hope you'll recover, I had many surgical operations on my right arm so I can definitely understand how it feels!

Every game.
https://www.youtube.com/watch?v=4GQPuuik1q8

Anything from Spiderweb Software.

Here's the last ones I played (I smoke everyday so I need a one-hand game): Hearthstone, Slay the Spire, Chroma Squad

Pretty much all point&click games can be played with only a mouse.

If you have or are willing to get a mouse with thumbpad like the Razer Naga or Logitech G600, you can open up a number of additional games. ARPGs like Diablo & Path of Exile. Several MMO's. Some MOBA's. Might be worth the investment even if it's just during the initial few weeks of recovery.

Any Turn Based Game
example series Xcom, Age of Wonders, Heroes of Might and Magic ect.
And older games Fallouts 1,2 and Tactics, Arcanum...

Bayonetta

I recommend Deep Sky Dertelicts, played with only a mouse, it's an interesting game with a nice art.

I've been trying to play with an injured arm recently, and I've been using Remote Play on my tablet with games like Slay the spire, Reigns and Hidden Object games. They all are great one handed!

https://store.steampowered.com/app/374400/VoiceBot/