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