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