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