Racing games in general, personally I like Forza Horizon 5, you could play it with WASD and a spacebar

It’s easy to overlook because of the graphics, but Caves of Qud is a really interesting game that fits your criteria.

It’s hard to explain just what it really is or what makes it great, but it has a good mixture of generated and written content that keeps it interesting.

The Curse of the Golden Idol is a detective-puzzle game that is easily played one handed, is cheap, and is great.

Invisible Inc is like a stealthy XCOM (which I see on your profile), and again, easily played one handed.

If you are into VR, Beat Saber has some one-handed songs and Pistol Whip is mostly one-handed. The exercise of playing those games improves overall circulation which helps the healing of fractures.

Civ

Civ 5

If you’re willing to bend on the RTS thing, Tooth and Tail is an RTS game that is almost completely played with your left hand in keyboard mode - it’s an RTS designed for gamepads so it only uses wasd and like 6 action buttons (rally selected, rally all, cycle selection forward, cycle back, build, sell). It uses the mouse buttons to click for the rally commands but not the pointing by default, you could rebind the mouse click rally commands to like lshift and ctrl or something like that and it should work well. But the single player campaign does get difficult towards the halfway mark

Civ V/Civ VI can all be played entirely with a mouse. Very fun, too.

Xcom: enemy within and xcom 2. FTL: Faster Than Light.

Anything that is turn-based will work really, or doesn’t rely on a real-time mechanic.

I do suggest looking at a small trackball that you can use in the meantime. It’ll be useful for the times when you need a pointing device in a smaller space, for whatever reason.

Steins;Gate and then Steins;Gate0

First thing that came to mind was FTL: Faster Than Light. I used to play on a laptop with no mouse and a lousy touchpad, so I became familiar with the hot-keys.

You can pause the game at any point to stage your attack / defense. Most commands have hot-keys you can press, rather than point and clicking. You might need to use the mouse for a few parts, but given the ability to always pause the game (I think it’s game mechanic really) you shouldn’t have too much trouble since you’re under little pressure to do so quickly.

I played through 'One Finger Death Punch" with a broken arm.

Would recommend.

You can play Earthbound on an emulator with one hand pretty easily. (bSNES is pretty good)

Oh god I know too much about this. Long comment. Sadlol.

What kind of cast? Above or below the elbow?

I had above the elbow for 9 weeks once and below 3 times for 3-6 weeks on my right arm. Only below the elbow on my left but 5 times. My bones aren’t so good.

Above the elbow I played a lot of Warcraft 3(long time ago lol), Civ, AoE etc. Games that only required simple clicking but lots of hot keys to control. Above the elbow cast prevents a lot of you ability to rotate your arm so switching the mouse to your left doesn’t help much.

Below the elbow it depends if your thumb is immobile or not. If your thumb is free then it’s a matter of buying a cheap small mouse that will fit in your palm with the giant cast bulge. FPS and fast movements will be painful and not recommended but slower games and general use isn’t much impeded.

Immobile thumb is maybe the worst. Grab a cheap number pad and place it under your hand so you can use four fingers on the buttons. Mouse in your left hand. This severely limits what you can do with a computer.

Look up some brain exercises to ease the transition between sides of your brain and handedness. Also hold on to the skills you develop in these few weeks. Being able to work right or left hand helps with a lot of manual tasks with weird angles like using a drill under a sink or what have you.