Happy Glass 3 is a logic-puzzle game that features semi-realistic physics, a drawing requirement and anthropomorphic glassware. The player's goal across 25 levels is to make drinking glasses happy by filling them with water from dispensers. They must use hand-drawn lines made of dots to direct the flow of the water past objects and gaps that prevent a glass from receiving it.
The player uses a pencil to draw the lines on the white graph paper background. They must draw slowly and carefully because the pencil only marks the paper with black dots. That said, unlike similar games, they can draw and redraw lines after the water starts to come out of a dispenser.
The water also flows as balls instead of a continuous stream, which means the player must prevent small balls from dropping between the line dots. The balls also stop rolling and flowing at different intervals. This action can prevent the water from dropping into a glass above the fill line in time.
Happy Glass 3 rewards up to three stars when the player does well. The game gives them plenty of challenges, including objects that are hard to draw around and water flowing in directions nowhere near a glass. The player must rely on their knowledge of gravity and physics to guide their solutions.
The game also rewards the player with coins. They use this money across three categories (Water, Pencil and Face) to perform color, design and mood upgrades, respectively.
