Yep, SAG-AFTRA. The problem is that certain game studios refuse to work with the union (for a variety of reasons, from minor stipulations of the union contract that can't be guaranteed, to simple staunch opposition).
Unfortunately the field is fraught enough that there are plenty of folks that need to work non-union sometimes, too. It's not the kind of job where you can just get hired once and show up for 40 hours for a paycheck. Projects are often short commitments - maybe a few hours at a time. More if you're lucky. And that's only after you throw your name into a million buckets, audition for as many as will have you, and hopefully get cast.
If you're real lucky, you get to do something like Genshin that will invite you back regularly to do voices for events, and you can show up for the work without needing to audition again and again like for everything else. Well. At least until they decide not to pay you for months, that is.
Uppercut, Unwinnable, and Into the Spine sound to me like what you're looking for. Paste has quietly raised up a lot of great games writers, too.
I also recommend reading lots of reviews for games you're interested in. Listen to spoilercasts about them. Pay attention to the bylines, and when a critic says something that gets your mind going, try checking out what else they've written. Most critics are active on social somewhere, and if you like what they have to say, they'll probably share other writing that's similar.