I want to pick up some stuff while the sale is still going on to broaden her horizon a bit.
So we have worked out that she does not care for story but likes mythological settings and building. She does not like being told what she has to go do.
As already mentioned, Skyrim should be at the top of your list.
Baldur's Gate 1 & 2 Enhanced edition if she hasn't played them, there is a lot of story, lore and text, its pretty opened ended, you can go where you like, do what you like(within the games parameters) and randomly bump into side quests and characters. Set in the Dungeons and Dragon universe, so game has a strong mythological setting, with sects, temples etc...
If you want to broaden her horizon then Dark Soul games, strong mythological settings with its own lore that you piece together throughout the game world. You are free to go and kill what you want but eventually you're going to have to stomach it and face bosses to progress or open up more of the world to explore. Game has a very hopeless isolating feel, like you're alone against the rest of the game world and anything can kill you. Shame the 1st game isn't on sale, its probably the best amongst them but requires DSfix. She will either love it or hate it, be warned game is not for the faint hearted.
Ori and the Blind Forest, metroidvania, game is a masterpiece.
Okami, strong mythology, an action adventure game like Zelda.