[The Core Mechanism]

In basic this is a Roll Over d100 system where the guesses the players make control the results of the dice.

The roll will be made in secret and then the players guess: the closest guess will decide the difference. You count that many numbers back from 100: this is the final roll. You then add the modifiers from the character's sheet and discover if the Target has been met. If it has, they succeed, if not, they fail. Guesses that fall within 4 of the target will be critical successes. (There Are no Critical Failures.)

Because each guess is another chance to get within 4 points of the target number the more players participate in the story the better thier odds of success become.