Here is the full list of all 22 Unium achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
Solve "Mushroom" by overlapping the line twice.
Solve "Lorry" by overlapping the window.
Solve "Punnett" by overlapping all four tiles in all three white squares.
Solve "The Only Card You Need" two ways: Once crossing the line on the center neutral tile, and once without.
Solve 50 Advanced puzzles
Solve 40 Advanced puzzles
Solve 30 Advanced puzzles
Solve 20 Advanced puzzles
Solve "Top Hat" by overlapping the line twice.
Solve "Helmet" by overlapping the line twice.
Make a moth out of "Flutterby" by turning all tiles white, except for 3,4 and 8,4.
Solve 10 Advanced puzzles
Solve "Spectacles" without using either of the neutral tiles.
Solve "Hot Coffee" without using the neutral tile.
Solve 30 Medium puzzles.
Solve 20 Medium puzzles
Solve 10 Medium puzzles
Solve "Fish" by overlapping the fish's eye.
Solve "Battery" by overlapping the line twice.
Solve "Imbalanced Load" by overlapping the line three times.
Solve 10 Easy puzzles
Solve 10 Beginner puzzles