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