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 one challenge.
Collect 25% of all relics.
In multiplayer, be the only player on your team that isn't dead or downed.
Complete the game.
Kill 40 enemies with the shotgun.
Purchase all skills in one category.
Find 25% of all documents.
Kill FeeFee the crab.
Kill 35 enemies with the pistol.
Kill 25 unaware enemies.
Force an enemy to drop dynamite that kills two people when exploding.
Kill 50 enemies with the bow.
Complete one optional tomb.
Perform 50 headshot kills in the single player campaign.
Find 75% of all documents.
Collect 75% of all relics.
Find 25% of GPS caches.
Find 75% of GPS caches.
Find all documents, relics and GPS caches.
Collect 5000 pieces of salvage.
Loot 200 enemies.
Purchase all skills in all categories.
Fully mod and completely upgrade any weapon.
Fully mod and completely upgrade all weapons.
Kill and loot 10 large animals (deer, boar, wolves).
Kill and loot 10 small animals (rabbits, chickens, rats).
Kill and loot 10 flying animals (crows and gulls).
Kill 75 enemies with the rifle.
Rope pull 5 enemies off edges.
Perform 15 finishers.
Shoot 10 enemies off zip lines.
Incapacitate 25 enemies with dodge counter.
Complete all optional tombs.
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.
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.