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