basically, you gotta press the colors that make up the shown color, the keys are red = 1, green = 2, and blue = 3, you gotta press them in numerical order, (e.g., cyan is 2,3, and not 3,2, if you try 3,2 you will lose a life or two), and the buttons besides the one in the very middle are mobile controls.
thanks to @create012345678 for the idea, he got it from another game where i forgot the name of :(