Accomplish the indicated achievement to get the corresponding number of Gamerscore points:

Marathon Tin Medal (5 points): Get 100,000 points playing Marathon.
Marathon Bronze Medal (10 points): Get 200,000 points playing Marathon.
Cascade Bronze Medal (10 points): Score 100,000 points playing Cascade.
Ultra Bronze Medal (10 points): Score 5,000 points playing 1 minute Ultra.
Race Bronze Medal (10 points): Clear 40 lines in under 4:00 playing Race (Single Player).
Score Bronze Medal (10 points): Get 25,000 points in under 10:00 playing Score (Single Player).
Hotline Bronze Medal (10 points): Get 25,000 points playing Hotline.
Eraser Bronze Medal (10 points): Clear eight target lines in under 1:30 playing Eraser (Single Player).
Go Low Bronze Medal (10 points): Get 30,000 points playing Go Low.
Back to Back (15 points): Do two Tetrises or T-Spins (Single or Double) without clearing any lines in between in Marathon.
Rollin On Spinnas (15 points): Pulled off the infamous T-Spin playing Marathon.
Marathon Silver Medal (15 points): Get 250,000 points playing Marathon.
Cascade Silver Medal (15 points): Score 200,000 points playing Cascade.
Ultra Silver Medal (15 points): Score 12,500 points playing 1 minute Ultra.
Race Silver Medal (15 points): Clear 40 lines in under 3:00 playing Race (Single Player).
Score Silver Medal (15 points): Got 25,000 points in under 7:30 playing Score (Single Player).
Hotline Silver Medal (15 points): Got 50,000 points playing Hotline.
Eraser Silver Medal (15 points): Clear eight target lines in under 1:15 playing Eraser (Single Player).
Go Low Silver Medal (15 points): Get 40,000 points playing Go Low.
Give Em Twenty (20 points): Send 20 lines in a Xbox Live game.
Back to Back and Back Again (25 points): Do three Tetrises or T-Spins (Single or Double) in a row (Back to Back to Back) playing Marathon.
Marathon Gold Medal (25 points): Get 350,000 points playing Marathon.
Cascade Gold Medal (25 points): Score 300,000 points playing Cascade.
Ultra Gold Medal (25 points): Score 25,000 points playing 1 minute Ultra.
Race Gold Medal (25 points): Clear 40 lines in under 2:00 playing Race (Single Player).
Score Gold Medal (25 points): Get 25,000 points in under 4:00 playing Score (Single Player).
Hotline Gold Medal (25 points): Got 100,000 points playing Hotline.
Eraser Gold Medal (25 points): Clear eight target lines in under 1:00 playing Eraser (Single Player).
Go Low Gold Medal (25 points): Get 50,000 points playing Go Low.
Live Playa (30 points): Win an Xbox Live game.
T-Spin Deluxe (30 points): Pull off a T-Spin 2-Line Clear playing Marathon.
Ludicrous speed (30 points): Clear a line on Level 15.
All about the Hamiltons (30 points): Score 100,000 points with Fill Rate set to High in Cascade.
Take it Off the Top (50 points): Clear line 20 of the Matrix.
Big Ol Cascade (50 points): Trigger 8 or more Cascade Line Clears with a single drop.
A For Effort (50 points): Play 100 games (Single Player).
Old Skool Back to Back (50 points): Score 2 Tetrises in 2 drops playing Marathon.
Went Low (50 points): Clear the Matrix completely playing Go Low.
Dirty South Style Back to Back (75 points): Score 3 Tetrises in 3 drops playing Marathon.
Marathon Platinum Medal (75 points): Get 500,000 points on Marathon.