Colorful Assort is a sorting game that features colored glossy balls and test tubes. The player sorts the balls so that each tube, known in-game as bottles, contains only one color of balls. When the player succeeds, the balls catch fire like flares and fizz with bright light and then fade slightly into the background.
The game forces several limitations on the player. They can't sort balls into full bottles across the levels or stages. They also can't sort one color of balls on top of a non-matching color. That said, the game provides the player with clear, empty test tubes to help make the process of sorting the balls easier and faster. Additionally, it allows the player to add extra containers if they agree to watch an advertisement video.
When the player selects a ball in a group of matching balls inside a bottle, the game automatically moves all identical balls from one container to the selected container. If they make a mistake, they can also undo their last move or reset the entire stage.
Colorful Assort makes gameplay more interesting as the player progresses through the levels by increasing the number of colored balls and containers. It also offers a unique form of play. It re-skins the colored balls with various graphics over time. For example, it replaces the candy-like, solid-colored balls with anthropomorphic heads in Stage 4.