Computer generates a random 3-unique-digit secret from numbers 1 to 9.  
As an example, 318, 571, 682 are all possible secrets.   But 322, 989 or 777 can not be secrets because it has duplicate digits.  302, 990 can not be secret either since it has 0.

The game is to guess the secret in as few steps as possible.  
Every time a guess is made, computer will indicate the number of correct digit and correct position.