Here is the full list of all 11 Grey Skies: A War of the Worlds Story achievements.
Fully upgrade Harper.
Complete the game!
Wash ashore on The Beach.
Take out 3 enemies with a single throwable.
Unlock all throwables.
Reach the Sewer.
Escape The Tripod.
Reach the caves.
Knock down your first enemy.
Scored a goal!
You did the farmer a favour.