Yeah I can believe that
I have sequence 1, 2, 3, 8 & 9 on 100%.
I did sequence 3 mission 6 and that was a pain

I had to stay undetected and kill 3 guards for 3 gate keys. Took me 4 tries I think. I also have 3 missions where I have to take no damage and the rest I don't know but shouldn't be that hard
