Here is the full list of all 35 Insurgency: Sandstorm achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Kill an enemy with a knife.
Navigate through chemical gas while wearing a gas mask.
Kill an enemy while blinded by a flashbang
Kill three or more enemies with a single grenade or explosive.
Kill an enemy after blinding them with a flashbang
Kill an enemy using the mounted weapon on a vehicle.
Capture 100 objectives.
Kill 3 enemies with a headshot in a row.
Destroy an enemy air support vehicle.
Get the first kill in a round.
Capture an objective as the last member of the team alive.
As a Commander, kill an enemy using fire support.
Kill an enemy by burning them.
Destroy an enemy weapon cache using a remote explosive charge.
Call in fire support ten times as an Observer.
Successfully rig and destroy an enemy weapon cache.
Kill an enemy with the last bullet of your magazine.
Kill an enemy while they are reloading.
Block an objective from being captured and then clear it.
Kill an enemy right after performing a speed reload.
Win a match of Checkpoint.
Kill an enemy by shooting through something.
Kill an enemy without using weapon sights.
Purchase your first item in the Appearance menu.
Kill an enemy with an enemy's live grenade.
Kill an enemy by bashing in a door.
Destroy an enemy vehicle with a mine.
Drive a vehicle full of teammates for more than 15 seconds.
Kill an enemy with a vehicle.
Kill an enemy driver with the mounted weapon of their vehicle.
Complete the tutorial mission.
Win a match of Firefight.
Win a match of Push.
Be the Most Valuable Player of a round.
Kill an enemy while vaulting.