Here is the full list of all 21 Armored Freedom achievements worth 1,000 gamerscore.
Kill a first enemy
Kill 8 enemies
Kill 16 enemies
Kill 50 enemies
Kill 100 enemies
Win a first match
Win 5 matches
Win 10 matches
Win 50 matches
Win 100 matches
Use a first action card
Use 5 action cards
Use 10 action cards
Use 50 action cards
Complete Mission 1
Complete Mission 2
Complete Mission 3
Complete Mission 4
Complete Mission 5
Complete Mission 6
Complete Mission 7