I think the queen could be player controlled but it would be very rare like a pot luck system or something.

Perhaps veteran players who have gained experience in the game could get the chance?

Or, even better, a player voting system, but only rogue ants who wish to break away from the curretn hill could vote which player becomes queen, and if the majority of the hill disapproves of the queen, she is voted on and, if kicked from queen position, a new player is elected.

EDIT: Didn't read all of evolutionsal's post; overthrowing rather than voting sounds a lot more fun! [evil]