Here is the full list of all 26 Greyhill Incident achievements.
Pick up the Manza-Manza Soda
Watch the TV News till the end
Finish Talk with Mr. Black
Pick up Keys Cameron VHS
Meet Bob
Aliens landed
Pick up Joe's drawing
Police arrives in Greyhill
The first Killed Alien
Bring the nails to bob
Hide somewhere
Knock an Alien with the Bat
Revolver Drum full of Ammo
Find 5 pieces of tin-foil
Meet Amy
free Matt
End of Father Grahams speech
Find Apone
Pick up Government Conspiracy Book
Repair the telecom. Pedestal
Call the mysterious man
enter Mr. Lafleches veranda
Meet Rachel
Rachel's Teddy with tin foil hat
Bob drives into the barn
The Ending