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.
Capture 100 objectives.
Destroy an enemy air support vehicle.
Win a match of Checkpoint.
Win a match of Firefight.
Call in fire support ten times as an Observer.
Destroy an enemy weapon cache using a remote explosive charge.
Kill an enemy with the last bullet of your magazine.
Purchase your first item in the Appearance menu.
Successfully rig and destroy an enemy weapon cache.
Capture an objective as the last member of the team alive.
Kill an enemy while they are reloading.
Navigate through chemical gas while wearing a gas mask.
As a Commander, kill an enemy using fire support.
Kill an enemy with an enemy's live grenade.
Kill an enemy while blinded by a flashbang
Kill an enemy by burning them.
Destroy an enemy vehicle with a mine.
Kill an enemy using the mounted weapon on a vehicle.
Kill an enemy driver with the mounted weapon of their vehicle.
Kill an enemy with a vehicle.
Block an objective from being captured and then clear it.
Kill an enemy right after performing a speed reload.
Kill an enemy without using weapon sights.
Kill an enemy while vaulting.
Kill an enemy with a knife.
Kill an enemy by bashing in a door.
Kill an enemy by shooting through something.
Kill 3 enemies with a headshot in a row.
Be the Most Valuable Player of a round.
Get the first kill in a round.
Kill three or more enemies with a single grenade or explosive.
Kill an enemy after blinding them with a flashbang
Win a match of Push.
Drive a vehicle full of teammates for more than 15 seconds.
Complete the tutorial mission.