Once you reach 750 points, open the door to the right of the mainframe with the carbine in it. When you hear the sound before the dogs arrive, have one person lay down in the corner. Note: This is the corner if you turn left immediately after you enter the room. Have the other person jump on top of him, then have both players crouch down. If done correctly, the dogs will go in the corner of the room to the left of where you are and will remain there. When they are there, shoot them. Note: This doesn't work with zombies.