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