Here is the full list of all 12 Monkey Island 2: LeChuck's Revenge achievements worth 200 gamerscore.
Finished the game in under three hours.
Completed the entire game
Finished the game without using one hint.
Finished the game using fewer than 10 hints.
Completed the game by using the object highlighting five times or less.
Guybrush inhaled some helium.
Called the LucasArts helpdesk when walking through the jungle on Dinky Island.
Completed Part Three: LeChuck's Fortress.
Allowed Guybrush to die.
Completed Part Two: Four Map Pieces.
Completed Part One: Largo Embargo.
Switched to classic mode at least once.