Here is the full list of all 20 Paper Can't Fly achievements.
Complete an easy level.
Complete a normal level.
Complete a hard level.
Complete an expert level.
Complete any level without dying.
Complete a hard level without dying.
Complete an expert level without dying.
Publish a level.
Create a level.
Play a level through the level editor.
Break another player's record in the leaderboards while competing against them.
Upvote a community level.
Reach maximum velocity.
Collect 10,000 total coins.
Collect 100,000 total coins.
Die 100 times.
Die 1,000 times.