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Fuck it. Imagine "Gears of War 3" written here in ASCII.
=========== CONTENTS=============== 
Same as all the other games.
Watch the cutscene at the beginning of the game. Then walk along the obvious path until the end of the game. Occasionally, the path might be interrupted by a cutscene or a shooting gallery section. Watch the cutscene or shoot all of the baddies from the fixed position and then go back to the beginning of this section, repeat until the game ends.
Sometimes you might find yourself exploring familiar scenes that have been mirrored. This means you have turned around and are walking the wrong way down the path. Turn around 180 degrees and then continue until you get a cutscene or shooting gallery.