Here is the full list of all 25 FLS achievements.
Get a score while playing any level
Get 10 000 Score on any level
Get 50 000 Score on any level
Get 100 000 Score on any level
Create and save a new map in the level editor
Download a map from the steam workshop
Gain ranks and total score to unlock Level 5
Gain ranks and total score to unlock Level 10
Gain ranks and total score to unlock Level 20
Gain ranks and total score to unlock Level 30
Gain ranks and total score to unlock Level 40
Gain ranks and total score to unlock Level 50
Gain ranks and total score to unlock Level 75
Gain ranks and total score to unlock Level 100
Have "Pink me" as your Most Played Map
Complete "Pink me" map
Play 10 different maps
Play 100 different maps
Reach 10k Total Score Gained
Reach 100k Total Score Gained
Create a new Map of Medium Difficulty
Create a new map of Hard Difficulty
Create a new map Of Very Hard Difficulty
Pass a Map without using the Mouse
Pass a Map without using Thrust