Here is the full list of all 20 Who Wants to Be a Millionaire? 2012 Edition achievements worth 1,000 gamerscore.
You used Walk Away 25 times.
You reached Round Two 10 times in a Two Player game.
You completed 10 Two Player games.
You used the Ask the Audience lifeline 10 times.
You answered the first question correctly 25 times without using a lifeline.
You played 25 games of Who Wants to Be a Millionaire 2012 Edition.
You used the Jump the Question lifeline 25 times.
You completed 10 One Player games.
You earned $5,000,000 in total winnings.
You answered the $1,000,000 question correctly five times.
You earned the Fastest bonus 10 times.
You completed Round Two without using a lifeline.
You completed Round One without using any lifelines.
You answered all Round One questions correctly.
You completed a One Player game.
You won a Two Player game without going to Round Two.
You completed a Two Player game.
You earned $1,000,000 in total winnings.
You answered a $1,000,000 question correctly.
You overcame a $20,000 deficit and won Round One in a Two Player game..