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