You didn't mention ages, but my kids liked the LEGO games. We played through Harry Potter, LEGO City Undercover, Marvel Superheroes, and Jurassic World, and there are a few more we haven't played yet. They'll run on a potato and they're really fun.

They aren't RPGs though, but for my kids, that didn't matter. They could role play just fine with the characters they could pick between.

Other than that, there are some others that may fit the bill, but they often have mature themes, like Divinity Original Sin and Wasteland, but hopefully those give you enough to find something that'll work.

I personally play a lot of single player games with my kids watching. We're playing through Zelda games right now, but we've played a number of games on PC as well. I'll sometimes let them control things for a bit if they want, but generally I'm the one actually playing.