The games are turn-based; each turn the enemy monsters advance one or more spaces and attack the player’s units if they are in range. The player must adjust the positioning of their units to either block the monsters from advancing and/or attack.

The story is based on alien invasion of a planet that has a dormant defense grid. As the player is re-activating the defense system with the assistance of a computer to control the machinery and with only limited resources, the aliens attempt to steal power cores.

The story revolves around the Order, an elite faction of wizards and warriors who guard the Rifts, magical openings between the human world and the ‘Dead World’, which provide a source of magical power throughout both worlds. Using this power, the Order is able to maintain a perfect world for humanity by using magic to manipulate nature.

In Plants vs. Zombies, players place different types of plants and fungi, each with their own unique offensive or defensive capabilities, around a house in order to stop a horde of zombies from devouring the brains of the residents.

The game begins as Cartman runs over to Stan’s house to warn him that ‘horrible beings’ are attacking South Park. The two are able to defend the household from an army of Ginger Kids and Cows before picking up Kyle and running to their school.