There are plenty of synonyms for the term "new ball game," which means a completely new and different situation or game altogether. Some commonly used phrases include a "fresh start," a "different playing field," a "new challenge," "changed circumstances," a "shift in gears" or a "game changer." These phrases all convey the sense that something significant has shifted, and a new approach is needed. Other suggestions might include "a whole new ball of wax," "a brand new game to play," and "a new set of rules." Whatever term you choose to use, the message is the same: it's time to adapt, adjust and be prepared for anything.