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