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