Here is the full list of all 50 Spec Ops: The Line achievements. It takes around 15-20 hours to unlock all of the achievements on Windows.
Play it smart.
Complete game on "FUBAR" difficulty.
Choose restraint.
Show mercy.
Kill 10 enemies while they use zip lines or are rappelling. (campaign only)
Follow your orders.
Kill 150 enemies with any heavy weapon. (campaign only)
Stun an enemy by dumping sand on their head. (campaign only)
Kill 75 enemies with any shotgun. (campaign only)
Kill 50 enemies with grenades. (campaign only)
Sprint into cover 10 times while under fire. (campaign only)
Live and let live.
Live and let die.
Carry on, soldier.
Complete any chapter with 60%+ accuracy without dying or reloading a checkpoint.
Complete game on "Walk on the Beach" difficulty.
Complete game on "Combat Op" difficulty.
Complete game on "Suicide Mission" difficulty.
You are relieved.
The end of the line.
Recover all Intel Items.
Blow up 10 explosive objects, killing at least one enemy each time. (campaign only)
Choose vengeance.
Kill an Edged Weapon Expert while he is up to 5 meters away. (campaign only)
Get out of here!
Stand united.
Kill 50 enemies with any sniper rifle. (campaign only)
Kick an enemy by vaulting over a cover. (campaign only)
Kill an oryx. (campaign only)
Save a bullet.
Kill 50 enemies using only the Attack Command. (campaign only)
Kill 250 enemies with headshots. (campaign only)
Kill 3 enemies with a single grenade. (campaign only)
Buck the chain of command.
Kill 350 enemies with any rifle. (campaign only)
Play it loose.
Kill an enemy by tagging him with a sticky grenade. (campaign only)
Recover 12 Intel Items.
Kill an enemy just as they are throwing a grenade. (campaign only)
Face the horrors of war.
Kill 4 enemies with a shotgun in 10 seconds or less. (campaign only)
Kill 5 enemies using blind fire. (campaign only)
Hit 10 enemies with your melee attack. (campaign only)
Engineer an exit strategy.
Kill 100 enemies with any pistol or SMG. (campaign only)
We have contact.
Complete three chapters in a row without being killed or reloading a checkpoint.
Look out below.
What's lost is found.
Recover one Intel Item.