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