Here is the full list of all 43 WET achievements worth 1,000 gamerscore. It takes around 15-20 hours to unlock all of the achievements on Xbox 360.
Complete Chapter 1 on any difficulty setting (Story Mode).
Complete Chapter 2 on any difficulty setting (Story Mode).
Complete Chapter 3 on any difficulty setting (Story Mode).
Complete Chapter 4 on any difficulty setting (Story Mode).
Complete Chapter 5 on any difficulty setting (Story Mode).
Complete Chapter 6 on any difficulty setting (Story Mode).
Complete Chapter 7 on any difficulty setting (Story Mode).
Complete Chapter 8 on any difficulty setting (Story Mode).
Complete Chapter 9 on any difficulty setting (Story Mode).
Complete Chapter 10 on any difficulty setting (Story Mode).
Complete Chapter 11 on any difficulty setting (Story Mode).
Complete Chapter 12 on any difficulty setting (Story Mode).
Finish Story Mode on Cake Walk (Easy) difficulty.
Finish Story Mode on Hired Gun (Normal) difficulty.
Finish Story Mode on Fixer (Hard) difficulty.
Finish Story Mode on Femme Fatale (Ultra Hard) difficulty.
Finish Story Mode on Golden Bullets difficulty.
Collect 1 Monkey Toy.
Collect every Monkey Toy in a single Chapter.
Collect every Monkey Toy in the game.
Get a balance of 50,000 Style Points (Story Mode).
Kill every Scorpion in Rubi's Boneyard.
Purchase any 3 upgrades.
Purchase all Rubi Ability Upgrades.
Purchase all Rubi Weapon Upgrades.
Purchase all Upgrades.
Earn a Bronze Medal in every Challenge (Boneyard Challenges).
Earn a Silver Medal in every Challenge (Boneyard Challenges).
Earn a Gold Medal in every Challenge (Boneyard Challenges).
Beat the target score in any Chapter (Points Count Mode).
Beat the target score in any 3 Chapters (Points Count Mode).
Beat the target score in every Chapter (Points Count Mode).
Kill a total of 200 Enemies using Rubi's Pistols during acrobatic slow-mo.
Kill a total of 200 Enemies using Rubi's Shotguns during acrobatic slow-mo.
Kill a total of 200 Enemies using Rubi's Sub-Machineguns during acrobatic slow-mo.
Kill a total of 200 Enemies using Rubi's Dart Bows during acrobatic slow-mo.
Kill 200 Enemies with acrobatic Sword attacks.
Kill 30 Enemies with environmental objects or explodables.
Kill 3 Enemies at the same time.
Kill a total of 100 Enemies while using stationary gun.
Kill 100 Enemies with headshots.
Kill a total of 100 Enemies at maximum multiplier (x5).
Reach a chain kill count of 60 while in Rage Mode.