Smiling Glass: Happy Smile is a physics-based game in which you have to fill a glass with water. You need to tap the screen with the right timing to release the water and make it flow all the way through to the cup. The levels are easy to play and have simple rules. The game is also filled with lots of different challenges, including spikes, moving platforms, and even other obstacles.

To play the game, you need to understand the physics of the water and the different elements. You also need to use your control to keep the water flowing and avoid the obstacles.