I have no personal experience with kittens playing in the litter box, but I do know that kittens go through stages of playing with things they shouldn't and then the next thing you know they aren't the least interested in that object anymore. Toilet paper is another item that will soon catch Star's attention.

Is there some way you can maybe put her box in a box with sides just a bit higher to try and contain the litter a bit? Other than that, just let her play and she will pass this phase quickly enough and be onto something else she shouldn't be.