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.
Kill 75 enemies with the rifle.
Fully mod and completely upgrade any weapon.
Kill and loot 10 small animals (rabbits, chickens, rats).
Purchase all skills in one category.
Kill and loot 10 flying animals (crows and gulls).
Find 25% of GPS caches.
Kill and loot 10 large animals (deer, boar, wolves).
Loot 200 enemies.
Collect 5000 pieces of salvage.
Kill 25 unaware enemies.
Perform 15 finishers.
Collect 25% of all relics.
Complete one challenge.
Find 25% of all documents.
Perform 50 headshot kills in the single player campaign.
Kill 50 enemies with the bow.
Complete one optional tomb.
Find 75% of all documents.
Collect 75% of all relics.
Find 75% of GPS caches.
Find all documents, relics and GPS caches.
Purchase all skills in all categories.
Fully mod and completely upgrade all weapons.
Kill 40 enemies with the shotgun.
Kill 35 enemies with the pistol.
Force an enemy to drop dynamite that kills two people when exploding.
Rope pull 5 enemies off edges.
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.
Kill FeeFee the crab.
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.