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