This movie answered a lot of questions about NGNL series. It tells the story of what happened 6000 years ago and how everything came to be as narrated by Tet the God of Games.

NGNL Zero Movie is one very good movie and I highly recommend watching it. But to fully understand and appreciate it, it's best that you finish season 1 first. I rate it 9/10 because the storyline and plot was just mind blowing.