Here is the full list of all 24 Sniper: Ghost Warrior achievements.
Collect all secrets.
Finish the game on Normal difficulty.
Finish the game on Hard difficulty.
Complete Act 4.
Finish the game on Easy difficulty.
Shoot 5 cable lines using sniper rifles.
Complete Act 3.
Kill a total of 30 enemies with Browning gun.
Kill 2 enemy with one shot.
Complete Act 2.
Kill all enemies attacking your pontoon from the riverside on 'Weaken The Regime' level.
Complete Act 1.
Deliver 100 headshots.
Kill 10 birds.
Kill 10 enemies with throwing knives.
Deliver 50 headshots.
Shoot an enemy through a wall.
Kill 15 enemy using concentration mode.
Win 50 rounds playing online. (Multiplayer)
Kill 2000 enemies. (Multiplayer)
Kill 250 people using pistol. (Multiplayer)
Kill 500 people using sniper rifle. (Multiplayer)
Kill 250 people using sniper rifle. (Multiplayer)
Kill 2 enemy with one grenade.