I just finished the game on The Boss Extreme and I can safely say that you cannot play like you ussaly do. Your stress meter goes up 4 times as fast as normal; your health can take about 10-20% of what you can on other diffucties and enemies can hear footsteps almost 20feet away(kinda over did their alertness). Your DREBIN POINTS carry over from your previous game so eventually you can afford that weird gun that makes a tornado. Do not pass up on this if you love stealth challenges, I know most won't like it but I loved it and I'm sure other stealth nuts like me will too.

I just started playing it on the boss extreme, you cant do anything wrong. If they see you run because only about 3 or 4 shots will kill you. Im almost done with act 1. Act 1 was very hard and I know its just going to keep getting harder. Good luck 2 you.