Besides problem-solving, deduction, and observation here are the other cool features of the Happy Glass game. They may look easy to solve, but they can get more challenging as the game goes on. And it becomes more interesting too. Check out these other features of the Happy Glass free game.

Dynamic mechanism that allows you to draw the lines
Smart puzzles that get progressively more challenging
More levels to come as updates as being made
Highly addictive and entertaining puzzle game
Stress-releasing mental challenges