Here is the full list of all 39 Return to Monkey Island achievements worth 1,000 gamerscore.
Freed Otis
Thoroughly Examined All Of Wally’s Stock
Convinced Cobb To Tell You About LOOM
Started Part One
Started Part Two
Started Part Three
Started Part Four
Started Part Five
Answered Ten Trivia Questions Correctly
Answered Twenty-Five Trivia Questions Correctly
Answered Fifty Trivia Questions Correctly
Answered Seventy-Five Trivia Questions Correctly
Answered One Hundred Trivia Questions Correctly
Collected More Than Twenty Trivia Cards
Died For Real
Fulfilled Your Restroom Obligations
Shared Your Luck
Attempted To Steal The Cook’s Mop
Told Everyone On Mêlée Island That You Are Looking For The Secret
Got Hired With All Four Mop Heads
Listed Every Mess On The First Swab’s Report
Braved The Scorched Alaska
Swabbed The Hold Twenty Times
Decked Out The Sea Monkey II With Spooky Skulls
Got To The Heart Of The Problem
Explored The Entire Ocean Floor
Found Cogg Island
Did Gullet A Favor
Offered To Donate To The Earthquake Relief
Performed The Ole Switcheroo With The Replica Flag
Became A Prize Chum
Rescued Wally From Monkey Island
Waited Patiently To See Carla
Ahoy! More Than Twenty Times
Let The Lumpsucker Escape
Found All The Copies of ‘At The End Of The Plank’
Reached The End In 2 Hours Or Less
Returned To The World You Know
Gave Stan His Toothbrush