Before you can unlock the true ending of Zero Time Dilemma, which can be found at the end of the leftmost branch of your global flowchart, you need to make sure you’ve explored every possible decision and outcome in the game thus far. Here are some key things you need to know and unlock before the game will allow you to progress to the true ending.
Q’s password: You’ll unlock the password to unlock Q’s head in the bad ending where he meets Zero after Eric and Mira escape the shelter. The password is 61404091.
Twins’ birthday: After solving the locker room puzzle after transporting to an alternate history, Diana and Sigma will come across a locked golden door. It’s called the Door of Truth in the global flowchart. The password is the birthday of Diana and Sigma’s twins children, which can be uncovered by completing the branch where the two are stranded in the shelter after using the transporter. Their birthday is November 16, 2029. The password to the door is 11162029.
Force Quit Box password: Zero will reveal the password of the Force Quit Box in the Zero ending where he kills everyone except Diana. The password is VIVE HODIE, which is Latin for “Live for today.”
Get everyone to live: Here’s a tricky thing that you might not have noticed. On the top left corner of your global flowchart are four icons: a thumbs-up icon, and three other different colored icons that represent the three teams. You need to get all four icons to light up before you can progress. This means that you need to replay the execution votes in order, and view the cutscenes where each time meets their demise. After that, replay the execution votes for all teams again, and have them follow the instructions on Gab’s note so that all of them live.
Once you’ve done all of the above, you should be able to access the leftmost branch of the global flowchart, allowing you to view the true ending of Zero Time Dilemma.