Board Thread:Questions and Answers/@comment-28847619-20160625220657/@comment-27701762-20160625220903

You have to fight Photoshop Flowey on your first run, no matter what. You cannot complete a True Pacifist run without first completing a Neutral run (i.e. by defeating Flowey).

If you haven't killed anyone, then you are simply not required to start over from the very beginning to complete the True Pacifist playthrough.