Complete the following tasks to unlock the corresponding achievement. To view your achievements and stats in Steam, select "Community", then "My profile", then "View all my games", then the game and view stats.

Achievement	How to unlock
Act 1	Complete act 1.
Act 2	Complete act 2.
Act 3	Complete act 3.
Act 4	Complete act 4.
Captain	Finish the game on Normal difficulty.
Close Range	Kill 250 people using pistol. (Multiplayer)
Electrician	Shoot 5 cable lines using sniper rifles.
Fallen Eagle	Kill 10 birds.
Flying Knives	Kill 10 enemies with throwing knives.
General	Finish the game on Hard difficulty.
Heavy Fire	Kill a total of 30 enemies with Browning gun.
Hold Your Breath	Kill 250 people using sniper rifle. (Multiplayer)
Laurel Wreath	Win 50 rounds playing online. (Multiplayer)
One Package, Two Receivers	Kill 2 enemy with one grenade.
One Shot, Two Kills	Kill 2 enemy with one shot.
Rookie	Finish the game on Easy difficulty.
Seeker	Collect all secrets.
Sharpshooter	Kill 500 people using sniper rifle. (Multiplayer)
Sniper Expert	Deliver 50 headshots.
Sniper Master	Deliver 100 headshots.
Supplier of Death	Kill 2000 enemies. (Multiplayer)
The Protector of Pontoon	Kill all enemies attacking your pontoon from the riverside on 'Weaken The Regime' level.
Through the Wall	Shoot an enemy through a wall.
You Have to Focus	Kill 15 enemy using concentration mode.