Do you have a version that requires more kills? At 20 or so it would be a useful admin login challenge. To make it less hackable it could perhaps submit which

Do you have a version that requires more kills? At 20 or so it would be a useful admin login challenge. To make it less hackable it could perhaps submit which monsters were killed and/or the time between kills or some other pattern. If the set roughly matches the previous attempts it could make for quite the challenge to brute force. The "hackers" are already complaining that the challenge is to much for them :p I think you are onto something.