Here is the full list of all 20 The Jackbox Party Pack 3 achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
Guess within 5% of an audience's answer
Play 3 games in a row with the same players
Answer 5 Trivia Questions in a row correctly
Get a score of 25 or more in the Math Killing Floor
Catch the Faker on the first vote.
Faker gets through three tasks in a row without a single vote (or two tasks for three player games).
Be the creator of every shirt in the final gauntlet
Win all your battles in Round 1, but lose all your battles in Round 2
Write "gravy castle" and win a battle with it
Get a Super Quiplash! (all player votes and 90% audience votes in a 5+ player game)
Create a custom game
Use all of your colors in a single drawing that then gets used on a shirt
Get all the votes in a single battle in a 5+ player game
Pick top three answers in final round
Perfect guessing of higher/lower
Guess the exact percentage
Survive The Killing Floor 3 times in one game
Vote against your own shirt in a battle
Play five games of Fakin' It in a row.
Play 40 You Gotta Point tasks.