In Stack Colors, your goal is to collect objects of a particular color and get as many of them to the finish line as possible. You can change the color of your character, which affects the color of the objects you need to pick up. You must also avoid picking up objects of other colors, as doing so will cause you to lose those of your own color, and if you lose all of them, the game is over. There are also areas where the color can change quickly, requiring you to react quickly in order to pick up the correct object.
You can play it with your mouse or, you can use left and right arrows to direct the character.