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