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