Cleo ignores the mousies any time we humans are around.  Actually, she
refuses to play when she thinks a human might be watching her.  We
keep finding the bathroom mat accordioned up against the tub,
straighten it, and find it accordioned again a half hour later.  We
know it is her running in there and taking little "rides" on the mat.
We just haven't actually caught her in the act yet.  Almost, but not
quite.  I have caught her batting a mousie around, but she stops as
soon as she realizes she is being watched and looks around with a
"bored with everything" look and then begins straightening her fur.
She does this because play is not a queenly thing to do, and she wants
us to only see her queenly side.  She is one of those cats who
believes that it is much better to sit behind a cracked open door and
wait for someone (human or cat) to enter the room (thus opening the
door for her) than to raise a paw to open the door enough to squeeze
through herself.  Lazy?  No.  She knows how to open the door but feels
a need to show how patient she is and make sure we, her subjects, know
we are there to serve her.  It's really quite funny since she will
push a door open anywhere, but she won't pull a door open even if she
is alone in the room and wants out.  She doesn't cry for someone to
come open the door either, she just sits in meatloaf position and
waits quietly until the door opens, then slips out.
Debra in VA