Not too far into the game there's a level where you pass in the sewer like area, where you meet those mutant things for the first time. After fighting your way through a hord of them and taking a lift, you end up on the roof in front of a large sky light. A helicopter will be there, and then fly away and soon the roof is swarming with enemies. I can easily dispatch them, but don't know where to go after that. There's two doors, but both just lead to rooms with ammo. There's another door behind a fence, but I can't seem to get past the fence. I'm not sure if I'm not going the right direction or if I need to pick up exsplosives or something. Please help! Is it me, or the game glitching? i no how to use the slow motion gavil thing? but i cant seem to guide it down to the red button how do i do it!? do i stand close to the dorr far im so confused i have been stuck on this for weeks???