Even without collecting the extra stuff, it extremely depends on how you play it. On the higher difficulties, you need to do everything planned and be very patient. Reminds me a lot of Hitman. I had to start over more than ten times at some checkpoints because I had made an unforgiving mistake resulting in instant death.
[Edited by madatcheats, 6/29/2014 11:02:53 PM]
Indeed, Playing this on ''Authentic'' everything you do from moving to shooting is based on precise action. 1 error its cost of life. Love this mode. makes the game seriously challenging and one has to take there time.. hours long missions to make sure you do everything precise!