Kill 10 guardians with headshots from the front while their shields are raised.

Start a character in multiplayer or customize a character in single-player.

Explore a lost city.

Defeat a Harvester.

Stop a Cerberus kidnapping.

Escape a Reaper in the galaxy map.

Visit a store in the single-player campaign.

Modify a weapon.

Defeat 20 enemies by shooting from the hip (without aiming with L1)

Destroy Turrets in Sewers

Blow up Ammo at Fortress

Defeat 70 enemies with the M4