I played Lost Pig, an interactive fiction game (i.e. text adventure), with Siglet Prime (age 6) a few weeks ago. It went swimmingly. We found lots of learning opportunities in the process. It’s not entirely a kids’ game, but it’s very kid-friendly, and a gentle introduction to the medium, as you can’t die or get stuck in an unwinnable state. It took us about two and a half hours with a 6-year-old typing, but a more reasonable time is probably more like an hour.
Of note, we can’t even get him to watch a movie for two straight hours, but he was fully engaged in this.
If you’re so inclined, you can try it in a browser.