To be utterly fair. The 2 main reasons why it was so difficult in the first place. Was in fact...
1. The easter egg itself being a 'random event' if you can call it that. So having to reset every time you spawn into a room filled with 'normal' students. Technically counted as an 'automatic game over' in my mind at least.
2. The very fact itself that the event was centered around 3 preds rather than just 2 apex preds. While it was rare itself, I count probably 6-10 of my deaths. To the 3rd non apex pred, Tulpy. Who at random times just decided to swallow my character and give me a game over. Since nightmare mode itself just has a higher chance of 'instant death' as I call it. It made even a little fairy a force to be well avoided.