Mastermind is a nice simple logical puzzle normally played as a board-game.
I've been bored so I have coded this up as a scratch game and placed it online.
Click on the link to go to the game [you only get the full coordinates if you complete the game on it's hardest setting [6 attempts maximum]
DISCLAIMER
WARNING: You are about to execute an online app in order to obtain additional information required to solve this puzzle. As the cache owner, I advise that this file is safe to run although the file needed to complete this geocache has not been checked by Groundspeak or by the Geocache Reviewer for possible malicious content. As a result, you are using this file at your own risk.