Ferals are kinda funny like that. They've been taught by their mothers not to play because it attracts attention of predators, so they really truly don't have any idea how to play. I know that Mary Anne (the feral queen as far as I'm concerned!) suggests with the kitten to bring in things that they know, like dried leaves or twigs.
Ophelia had no idea how to play when we got her, and she was only ~6 weeks old. She learned from watching Trent (they were kittens together). She doesn't play a lot, but when she does...look out!
Even Annie, who was friendly but found in the forest, didn't know what to do with a ball or a feather toy. She figured it out pretty quick and hasn't stopped playing since.
She's a little dolly! I see she's figured out the innocent look, even if she hasn't figured out toys yet!