Full list of all 50 Just Cause achievements worth 1,000 gamerscore. It takes around 25-30 hours to unlock all of the achievements on Xbox 360.
Liberated 11 Provinces In San Esperito
Completed Story Mission 14
Completed 20 Sea Vehicle Stunts
Completed All Stunts
Completed Every Race Mission
Completed Race 7
Completed Race 1
Completed 50 Side Missions
Completed 40 Side Missions
Completed 30 Side Missions
Completed 20 Side Missions
Liberated Every Province In San Esperito
Liberated 22 Provinces In San Esperito
Completed 10 Side Missions
Completed All Story Missions
Completed Race 2
Completed Race 4
Completed Race 3
Completed Race 9
Completed Race 5
Base Jumped From 1000 Meters Or Higher
Completed Collect Mission 3
Completed Every Collect Mission
Completed 45 Takeover Missions
Completed Collect Mission 4
Completed 30 Takeover Missions
Completed Collect Mission 5
Completed Collect Mission 6
Completed Collect Mission 13
Completed 15 Takeover Missions
Survived For 5 Minutes With Maximum Wanted Level
Survived For 2 Minutes With Maximum Wanted Level
Survived For 1 Minute With Maximum Wanted Level
Completed Collect Mission 10
Killed 500 Enemies
Completed Collect Mission 9
Completed Collect Mission 11
Completed Story Mission 7
Completed 20 Air Vehicle Stunts
Completed Race 6
Completed Race 8
Completed Collect Mission 7
Killed 250 Enemies
Completed Collect Mission 12
Completed Collect Mission 2
Completed Collect Mission 8
Completed 20 Land Vehicle Stunts
Completed 20 Car-To-Car Jumps
Completed Collect Mission 1
Killed 100 Enemies