Here is the full list of all 44 London 2012: The Official Video Game achievements worth 1,000 gamerscore.
Have run a distance of 42.195km over your career
Completed a Challenge Set with 4 players
Performed 10 ace serves over your career
Won a Table Tennis or Beach Volleyball match without losing a point
Won an Events Mode session with four players competing
Emoted first out of a group of players while being introduced for a race event
Earned 9 Challenge Stars in a single Challenge Set
Completed all Challenge Sets for a controller type
Every player in a Challenge Event scored more than their share of the team's 3-Star target score
Unlocked all available sporting accessories
Perform 10 Power Shots in a Table Tennis match
Hit the bullseye camera of the archery target, while representing a nation
Earned a Gold medal in every Versus event, while representing a nation
Performed 30 foul attempts in field events over your career
Wore an alternative national kit in an event
Beat your own personal best set in every event possible, irrespective of gender.
Earned 3 Gold medals in team events
Earned a Gold medal in every Throwing event, while representing a nation
Beat your personal best in Team Archery or Synchronised Diving
Earned a Gold medal in each of the 5 types of Swimming event
Touched the last hurdle and still won a medal in 110m Hurdles
You have won a total of 5 Gold medals in Quick Matches or Custom Matches
Earned a Gold medal in every Jumping event, while representing a nation
Earned a Gold medal in every Gymnastics event, while representing a nation
Earned a Gold medal in each of the 4 types of Track events
Earned the Gold medal in every event of a medium or hard Olympic Games mode campaign
Earned 20 medals in a single Olympic Games Campaign
Qualified for the finals of every event in an Olympic Games mode campaign
Completed the Men's K1 Kayak Single course with no penalties at all, while representing a nation
Hit every target at Station 4 in Skeet
Earned a Gold medal in every Shooting event, while representing a nation
Scored ten or more on every target in a round of Rapid Fire Pistol, while representing a nation
Created and played through a custom playlist
Won a Race by 0.07 seconds or less
Used a Retry Token, and got a better result in the top 3 places
Touched the bar in a High Jump and still cleared it successfully
Received a perfect ten from one of the judges in a Diving event
Earned a Gold medal in The Olympic Games mode
Qualified for the finals of an event in The Olympic Games mode
Won an Xbox LIVE Tournament
Played an Xbox LIVE Tournament with one or more friends
Broke a World Record
Completed a multiplayer game, while representing a nation
Competed in a Quick Match or Custom Match for National Pride