Here is the full list of all 50 Tomb Raider achievements. It takes around 40-50 hours to unlock all of the achievements on Windows.
Complete the game.
Purchase all skills in all categories.
Complete all optional tombs.
Fully mod and completely upgrade any weapon.
Find 75% of all documents.
Collect 75% of all relics.
Find 75% of GPS caches.
Kill and loot 10 flying animals (crows and gulls).
Kill FeeFee the crab.
Loot 200 enemies.
Perform 15 finishers.
Kill 25 unaware enemies.
Purchase all skills in one category.
Kill 35 enemies with the pistol.
Collect 5000 pieces of salvage.
Force an enemy to drop dynamite that kills two people when exploding.
Find 25% of GPS caches.
Perform 50 headshot kills in the single player campaign.
Kill 50 enemies with the bow.
Kill and loot 10 small animals (rabbits, chickens, rats).
Collect 25% of all relics.
Find 25% of all documents.
Complete one optional tomb.
Complete one challenge.
Kill and loot 10 large animals (deer, boar, wolves).
Find all documents, relics and GPS caches.
Fully mod and completely upgrade all weapons.
Kill 75 enemies with the rifle.
Kill 40 enemies with the shotgun.
Rope pull 5 enemies off edges.
Shoot 10 enemies off zip lines.
Incapacitate 25 enemies with dodge counter.
Complete all challenges.
Shoot a bundle of dynamite out of the air.
Complete all conversations with the Endurance crew.
Complete a match in all multiplayer modes.
Kill 20 enemy players in multiplayer using a turret.
Kill a zip-lining enemy player in multiplayer.
Catch a player in a snare trap in multiplayer.
Survive 10 explosions in multiplayer.
Revive a teammate in a multiplayer match.
Win a ranked match in every multiplayer mode.
In multiplayer, be the only player on your team that isn't dead or downed.
Kill 10 multiplayer enemies using your melee attack.
Kill 2 multiplayer enemies with a single explosive.
In multiplayer, escape death 3 times by using the rope ascender.
Purchase a new multiplayer character.
Reach level 10 in multiplayer.
Buy every upgrade and character in multiplayer.
Reach level 60 in multiplayer.