Falling Balls is a candy-themed, ball-and-cup game. It requires a player combine common sense with knowledge of geometry and physics to move colorful candy balls, blocks and other shapes of different sizes through a soil-like medium and funnel into a pink, heart-shaped box on a pedestal below the bottom of the screen.
The player must dig tunnels to move the balls from a pit at the top of the playfield to the funnel. Since the pit doesn't contain enough balls to fill the box, the player must also breach oubliettes filled with white balls and other shapes to transform them into multicolored candy.
The player needs to understand how gravity and momentum aid the fall of objects in the real world. They must know how friction and obstructions can prevent objects from falling as well. Obstacles include immovable ramps and shelves that act as barriers, rotating fan or mixer blades that block and toss the shapes everywhere and red holes that make them disappear forever.
The game also features an element of chance. If the balls and other shapes don't move fast enough through a tunnel above the funnel, they become stuck in it. Although the player can tunnel under white shapes, they hang unreachable in the air instead of falling like colored ones. Falling Balls also autoscrolls, which means the player can't always see dangers when creating tunnels or scroll back up the screen.