Fun in a box
You wouldn't believe how much fun your cat could have with a simple cardboard box. She can hide things inside, or hide inside it herself. And if you have two cats, you may even find they like hiding from one another in a game of hide and seek!
Don't just give her any old box. Make sure you find a nice and sturdy one so that she can climb out after she climbs in, and also that she isn't chewing it as well as playing in it. Try putting a little toy mouse on a string and dangling it in front of her. She'll know it's not a real mouse, but, depending on her mood, she may be willing to humour you for a while. Then she can indulge herself in fantasies of being a ferocious hunter out stalking prey.
Mix it up
This game can keep your cat amused and active for quite a while. Dangle the fake mouse in the air, or drag it along the ground to mix things up for her. Also, you could try a feather or another object your cat can bat her paw at. Just make sure you move your hand away quickly so you don't get scratched.