Patient Gamers

You may also consider a vertical mouse.

There are cheap but decent ones on Amazon, Kysona and Nulea (I think? sp?) make some, and there are also rather expensive ones.

Basically, you hold the mouse as if you are holding a cup of soda, like you're pounding your fist on the table, not palming the table.

They were basically mainly marketed as ergonomic, for carpal tunnel sufferers... but when you think about it, a very long gaming session, everyday, all the time, whatever... yeah the ergonomics do actually make more sense, they're fairly close to the same grip and shape of many trackball mice.

Alternatively, get a new Steam Controller when they come out in a few months.

Its a controller; sticks, buttons, pads triggers, also has two little uh, kinda like laptop track pads.

Its basically a Steam Deck w/o the screen in the middle, but lighter and more ergonomic.

I play older shooters (often emulated) with sticks, newer ones with a pad.

As far as a third person shooter that works well with controllers?

Uh...... Splinter Cell Chaos Theory?

You can get that on Steam.

Metal Gear Solid V?

Those are both probably narrative driven though, MGSV has multiple open worlds, basically?

???