Here is the full list of all 12 Chessformer achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
Complete 48 levels.
Complete 44 levels.
Complete 40 levels.
Complete 36 levels.
Complete 32 levels.
Complete 28 levels.
Complete 24 levels.
Complete 20 levels.
Complete 16 levels.
Complete 12 levels.
Complete 8 levels.
Complete 4 levels.