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