Full list of all 41 Gray Matter achievements worth 1,000 gamerscore. It takes around 15-20 hours to unlock all of the achievements on Xbox 360.
Finished "Houdini's habitat" Puzzle Set
Finished "Dread Hill House" Puzzle Set
Finished "Lambs for Dr. Styles" Puzzle Set
Finished "The Events at Horspath Track" Puzzle Set
Finished "Sam plays Lab Assistant" Puzzle Set
Finished "Sam gets carded" Puzzle Set
Finished "The Mysterious Dr. Styles" Puzzle Set
Finished "The Betrayer's Price" Puzzle Set
Finished "A Spectral Presence" Puzzle Set
Finished "Psi and Psi again" Puzzle Set
Finished "Memory of a Summer's Night" Puzzle Set
Finished "A Message from Laura" Puzzle Set
Finished "There was Something in the Water" Puzzle Set
Finished "A Plant in the House" Puzzle Set
Finished "Setting a Trap" Puzzle Set
Finished "C Railer Swoll " Puzzle Set
Finished "Psi and the Mind" Puzzle Set
Finished "The Experiment" Puzzle Set
Finished "A Day in the Rowboat" Puzzle Set
Finished "What Happened the Day Before" Puzzle Set
Finished "Investigating the Lambs' Club" Puzzle Set
Finished "The Ghost of Dread Hill" Puzzle Set
Finished "Altering the Plan" Puzzle Set
Finished "Terror in the Dinning Hall" Puzzle Set
Finished "Suspicions about Samantha" Puzzle Set
Finished "In the Lab" Puzzle Set
Finished "Where is She Now?" Puzzle Set
Finished "The Game of Life" Puzzle Set
Finished "In the Lion's Den" Puzzle Set
Finished "I'm Laura Styles!" Puzzle Set
Finish the game under 5 hours
Finished "That Piece of Junk" Puzzle Set
Play 1000 dialogs
Put all wild flowers into vases
Speak with Mrs. Dalton about the bike
Win the "Divide and Conquer" game without losing any hand
Fully Succeed the Ball and Cup trick
Completed your very first magic trick
Got your first memory flash
Finish the game with all bonus points
Finish the game