Here is the full list of all 25 Linelight achievements.
Reach the end of World 1
Reach the end of World 2
Reach the end of World 3
Reach the end of World 4
Reach the end of World 5
Reach the end of World 6
Complete the Epilogue
Collect all World 1 Yellow Stars
Collect all World 2 Yellow Stars
Collect all World 3 Yellow Stars
Collect all World 4 Yellow Stars
Collect all World 5 Yellow Stars
Collect all World 6 Yellow Stars