Here is the full list of all 18 Picross Touch achievements. It takes around 30-35 hours to unlock all of the achievements on Windows.
Completed a total of 500 puzzles.
All original 15x15 levels complete.
All original levels complete.
All original 10x10 levels complete.
Completed a total of 200 puzzles.
Submitted a 20x20 puzzle to the workshop.
Submitted a 15x15 puzzle to the workshop.
Submitted a 10x10 puzzle to the workshop.
Submitted a 5x5 puzzle to the workshop.
Completed a total of 100 puzzles.
All original 5x5 levels complete.
Completed a total of 50 puzzles.
Completed a total of 25 puzzles.
Completed a total of 10 puzzles.
Completed the tutorial.
Completed a total of 750 puzzles.
Completed a total of 1000 puzzles.
Completed a total of 2000 puzzles.