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
eating the brains of the residents. The playing field is divided into a
number of horizontal lanes, and with rare exceptions, a zombie will
only move towards the player's house along one lane (the main exception
is if it has taken a bite out of a garlic). Most plants can only
attack or defend against zombies in the lane they are planted in. In
later levels, players can purchase upgrades so as to adapt their lawn mower to new environments like pools or rooftops.
The game uses several different level types and layouts. The game
starts out in a front yard, and progresses to nighttime levels, where
the gameplay is more challenging, with no replenishing sun unless
specific plants are used, the backyard is visited, with a pool added,
and the final levels are a lighting storm level in pitch black, and
rooftop levels. Sporadically through the game, the player is either
warned through a letter by zombies or addressed by Crazy Dave to prepare
for an ambush, where the game takes on a bowling style, using walnuts
to bowl down zombies, or a modified version of regular levels, where
random plant types come up on a small selection, and the player can use
the plants without spending sun.
The player starts with a limited number of seed pack types and seed
pack slots that they can use during most levels. The number of slots can
be increased through purchases with in-game money. At the start of a
level, the player is shown the various types of zombies to expect and
given the opportunity to select which seed packs to take into the level.
Several plants are nocturnal, such as mushrooms, having a lower
sunlight cost, and are ideal for nighttime levels. Certain plants are
highly effective against specific types of zombies, such as the
Magnet-shroom, which can remove metallic items from a zombie, such as
helmets, buckets, ladders, and pogosticks.
The zombies also come in a number of types that have different
attributes, in particular, speed, damage tolerance, and abilities.
Zombies include those wearing makeshift armour, those that are able to
jump or fly over plants, and a dancing zombie which has different
designs depending on the version that is able to summon other zombies
from the ground. At various points the player will be inundated with a
huge wave of zombies. On the final stage the player must face a huge
robot operated by a zombie known as Dr. Zomboss.
