Yes, it's Hansel and Gretel. Nothing is changed. Well, the names of Hansel and Gretel are changed. Oh, and the witch is now a Krillitane. But otherwise, it's the same story. Kids in the woods find a gingerbread house, the owner captures them, they kill the owner and escape. The Krillitane is a fine choice to substitute for the witch, but really, I don't know what the point is. Maybe a fairy tale to read to kids who like Doctor Who but don't already know the Hansel and Gretel story?

I can see this being told as a fairy tale to time lord children, it's basically just a retelling of Hansel and Gretel, and this time the Doctor Who twist on it still feels more fairy-tale.

Sure it's an alien planet, an alien threat, and there's technology mentioned, but the core of it is still much the same, and the Krillitane is seen as much more witchy through the lens of a child, which i think works to this story's benefit!