Here is the full list of all 12 The Secret of Monkey Island: Special Edition achievements worth 200 gamerscore.
Completed Part One: The Three Trials. Guybrush proved himself worthy to be a pirate.
Guybrush learned all of the insults, and is the wittiest/deadliest pirate what ever swung a sword.
Guybrush can hold his breath for 10 minutes, but not any longer than that.
Experienced the original, classic adventure game, as it was in the early 90s.
Completed Part Two: The Journey
Complete Part Three: Under Monkey Island.
Complete Last Part: Guybrush Kicks Butt.
Collect all of the notes and memos on Monkey Island™.
Play both endings of the game.
Finish the entire game in under 3 hours.
Don't use any hints to finish the game.
Escape from the Monkey Island™ Cannibals' hut 5 times.