Happy Filled Glass 3 is the third physics-based logic-puzzle installment in the Happy Filled Glass series. The game features 30 levels. The player must direct water from a dispenser into an anthropomorphic glass that becomes joyous when the water reaches its fill line. They must also attempt to keep three gold stars per level.
The glass rests on a light, mint-colored shelf in front of a graph-paper-covered wall near the bottom of the screen. The water flows when the player selects the gray dispenser mounted high on the wall. The game blocks the water with objects placed between the dispenser and glass, including balls, blocks, boards, shelves and walls. As with previous games, it also features heating elements that turn the water into steam.
The water behaves like a viscous fluid and combines a thick flow and individual balls. The player can only bypass obstacles and direct the flow by using objects on the playfield and a pencil that allows them to draw barriers, channels and walls. For example, they can draw a barrier next to a heating element to prevent water from touching the surface.
That said, Happy Filled Glass 3 depletes a blue horizontal bar above the field that controls the number of stars the player collects on each level. They lose stars if they allow the bar to disappear too much.
The game also features a gravity-reversal machine. The player can suspend the water midair, pull it away from a trap, and then drop it on a desired spot.