Happy Filled Glass 4 is another logic-puzzle game in the Happy Filled Glass series that shares elements with the popular Happy Glass games. The player's goal is to bring joy to an empty anthropomorphic glass across 100 levels by filling it with blue water from a dispenser.
The glass rests on a light blue shelf near the bottom of the playfield in front of a wall covered with graph paper. The player must use objects on the field between the glass and dispenser to direct the flow of water. They can also draw barriers, channels and walls with a pencil. That said, the game features a secondary challenge. Each level starts with three gold stars. The number of stars the player collects depends on how much graphite they use to draw the lines.
Happy Filled Glass 4 presents the player with a lot of obstacles and traps. The player must direct the water into the glass while dealing with stationary and moving balls, shelves, paddles and other geometric forms. Heating elements and anti-gravity fields cause the water to become steam or float out of reach, respectively. The thick, viscous nature of the water makes it more solid than natural water. It can fall as a thick flow or become round balls.
Additionally, the game features magnets that attract water and suspend it in the air or next to a surface. The player collects the water and then dispenses it by restoring gravity. The game also features portals that teleport the water instantaneously from one area to another that's further away or on the other side of an obstacle.
