You have to shoot the falling bubbles. At the same time, your ball periodically changes color depending on the filling of the scale in the lower right corner.
Bubbles falling from above also have different colors. The bubble itself is transparent, but it leaves a color trail. To knock down a falling object, your ball must be the same color as the bubble you want to knock down. Miss three times and the game ends. So that you can focus on them and, on occasion, improve the result.
