Gears of War 2 - When you've killed enough grubs, the roof you are standing on will collapse. You will fall several stories, down to ground level. It's kind of like a one way elevator.

Home > Games > Gears of War 2> Large Screenshot
When you've killed enough grubs, the roof you are standing on will collapse.  
You will fall several stories, down to ground level.  It's kind of like a one way elevator.