Mode 1:
You pick the range(eg. 1 - 1000) and your phone will pick a number in that range. You have to guess it. It will tell you to guess lower or higher.
Mode 2:
You pick the range(eg. 1 - 1000) and a number and your phone will try to guess the number you are thinking of. You tell the phone to guess higher or lower or if it guessed correctly.