Fathom is an multiplayer on-line game alike to Mastermind. You try to guess the squence of the 4 coloured balls in as few guesses as possible. You get clues for every guess. The clue lets you know how many balls you have in the correct spot, how many you have that are the correct colour but in the wrong spot, and how many balls will not be used to complete the code.You will need The Lobby from www.tams11.com to play on-line.