The player controls Mario or Luigi and keeps blocks with monsters inside that are falling from the top of the screen from piling high enough to reach the top. Mario and Luigi try to prevent this by switching the different columns of enemy characters so they are positioned under different falling objects. If there is a chain of monsters within two Yoshi egg shells, the egg shells will merge and a Yoshi will form, adding points and eliminating a group of monsters. The larger the chain of monsters between the two eggshells, the more powerful the Yoshi that is created will be.