Here is the full list of all 12 Grey Skies: A War of the Worlds Story trophies - there are 11 gold and 1 platinum.
You shall henceforth be known as "The Common Cold".
Score a goal.
Do the farmer a favour.
Fully upgrade Harper and become an honourary Northerner.
Unlock all throwables.
Reach the caves.
Successfully escape the Tripod.
Reach the sewer.
Wash up on the beach.
Complete the game.
Neutralize 3 or more enemies with a single throwable.
Defeated your first enemy.