How to Play a Game?

On the screen, we gave an constructions that one of them is for example a Pisa Tower, there are people around the Pisa Tower and we gave the approximate length of a people. According to the length of people, we want player to estimate length of the Pisa Tower. There are also feedback according to the estimation of the player like close, perfect etc. These feedbacks give directions to the player and player can change his/her estimation according to the directions