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