Board Thread:Plants vs. Zombies 2/@comment-25961794-20160115130500/@comment-27380951-20160116020933

My theories of the time crack, which probably requires all trophies to unlock:
 * Like Master3530 said, the final boss. The player earns Modern Day trophy after Modern Day - Day 32 (instead of Taco or Silver Sunflower Trophy), and Dr. Zomboss could say something like "This isn't over yet! I will call reinforcements to complete my project! You can't stop me!" then he flees to the time crack. Unlocking the time crack initiates the final battle.
 * New Game+ mode. Tapping it to start the adventure again with harder difficulty. Worlds have to be unlocked again with World Keys (this is why you gain it at the end of Modern Day 16) and most levels have an extra flag with Crazy Dave choose 3 random plants for you in normal levels.
 * A simple "Watch the ending again" option that allows you to replay the credits sequence without fighting the final boss again.