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The building is about to collapse.
Before it does, quickly walk to the left and use the door. In the next room is Henry on the floor. There’s not much you can do for him but he gives you a KEY. Quickly use the door on the left to be guarded for the collapse.
Pick up the long metal PIPE from the floor and use the pipe on the tungsten slab on the floor. Pick up the sledge HAMMER from the corner and use it on the slab to give the pipe a sharp edge. Pick up the PIPE again and pick up the SLAB. Put the slab against the broken door on the left and use the sharpened pipe on the door to wedge it open. The slab will make sure it stays open.
Go through the opening to the green hub. You need to reach the open door on the left but be careful with the tiles. Use the tiles with the least cracks. Eventually use the door on the left to get to the green hub. There’s a security guard on the floor and he has a gun. Pick up the GUN and use it on the padlock on the emergency exit. Open the emergency exit and climb the ladder to the top.
Game source: A copy of the game was found here  on the internet.