HITMAN 2

Cannot praise this video enough. Took me a couple of tries to get to the save point, but an unbelievablely smooth run overall. Eighteen challenges completed for 52,000 XP, took me all the way from 5 to 14.

I was having trouble consistently knocking out the two guards in the Security Room with the briefcase/subdue method. So for anyone else struggling:

When you get to the Security Room, instead of opening the door, crouch and move along the glass wall keeping it on your right as you turn the corner. Up ahead will be a camera and if you use Instinct Vision, you'll see where it captures and the guy watching the screens in the room on your right. When you see the guy in the room walk away from the screens, make your move. I tried to do it while he's watching, but 47 gets caught in the level geometry when you get close to the camera despite the wall being a flat surface. But if the guy is not standing watching the screens, you won't get caught if you go by quickly and you're destroying the security system anyway.

Next, after getting under the camera, turn right a final time and unlock the cabinet on the back wall of this alcove with your lock pick. Inside is chloroform, and if you turn around 180 degrees from the cabinet, you'll see the door into where the armored vehicle exit is parked and right past that the ventilation system for the Security Room. In the room with the ventilation system are two guards, but they are looking away and won't spot you. Just make your way to it and add the chloroform.

Now go back to the cabinet where you got the chloroform and on the right wall you'll see the controls for the Security Room air conditioner. Interact with it to flood the room with chloroform, knocking out the 2 guys inside. Be sure to interact with the air conditioner controls again to clear the gas before entering the Security Room.

It takes a little longer, but I found it to be more reliable than the suitcase toss...