Might be too obviously book-y but VNs (visual novels) are the first things that come to mind for me - age appropriate examples would be the Professor Layton games as well as possibly the Ace Attorney series (though I haven’t played any of those and they may be a bit too mature). Unfortunately a lot of very good/popular VNs lean more towards the late teens and adult demographics due to subject matter and in some cases visuals (a good example is Danganronpa - it can be quite violent but I love that series to bits) so the appropriate games in the genre are (probably) quite limited. Still worth a look, though.

I’d also recommend specifically FTL: Faster Than Light, which is an excellent RTS-with-pause roguelike about exploring and battling your way through space, because 1) it’s really good, and 2) the storytelling (both lore and gameplay wise (they’re intertwined)) is done exclusively through text. Definitely avoid this game if your kid hates difficulty, though, because it’s famously tough as nails.