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