I, Zombie

I, Zombie is a group of Puzzle Mode levels where the player must plant zombies (they must be planted behind a line) to overcome cardboard plants and get to the end of each row, where there is a brain that the zombies must eat. The level is over when all of the brains have been eaten. At the beginning of the first level, Crazy Dave tells the player that the zombies want practice invading houses, and as he didn't want any plants harmed he put cardboard plants on your lawn. It's the belief of some players that Crazy Dave made the plants come to life with his Magic Taco.

After every three levels of I, Zombie Endless, a Present, Chocolate, a money bag with gold coins or a money bag with a diamond usually drops, although it will not always happen.

Strategy
I, Zombie is a very strategic puzzle game. First you must find ways of getting Sun, whether it is using Bungee Zombies to take Sunflowers, Gargantuars to smash them, or other zombies to eat them. Also, the player must have good understading of the abilities of both plants and zombies. For example, if a row has only a few cardboard Peashooters, it is safe to say that planting a Buckethead Zombie or a Football Zombie will earn you a brain and further you to completing the level. You can't take back zombies you've placed, so plan wisely according to your amount of sun.

Levels
There are 10 levels of I, Zombie, which in succession get harder. All of the levels take place in the equivalent of the Night stage of the game, presumably so the player can only get Sun from getting rid of Sunflowers.
 * I, Zombie
 * I, Zombie Too
 * Can You Dig It?
 * Totally Nuts
 * Dead Zeppelin
 * Me Smash!
 * ZomBoogie
 * Three-Hit Wonder
 * All your brainz r belong to us
 * I, Zombie Endless

Trivia

 * The I, Zombie games are one of the in-game appearances of Brains, the others being the mini-game Zombiquarium, Versus Mode, and the music video.
 * "I, Zombie" is a reference to the book I, Robot.
 * "Dead Zeppelin" is a reference to the band Led Zeppelin.
 * "Three-Hit Wonder" is a reference to the term "One-hit wonder" (the number three comes from the number of hits the Imp can take).
 * "All your brainz r belong to us" is a reference to the internet meme "All your base are belong to us".
 * In the level Me Smash! Gargantuars smash the brains (and a squashed brain image appears on the ground) instead of eating them.
 * Gargantuars can still throw their Imps in I, Zombie, but this does not usually happen; as Gargantuars are only capable of throwing their Imps if they are less than halfway across the lawn and the line marking where zombies can be planted is halfway across.
 * When Versus Mode was announced, and that Brains would be used as the equivalent to Sun for the Zombies, many people speculated that I, Zombie would now use Brains instead of Sun. However, this was not the case. It could be due to either time constraints, or to simplify the programming.
 * The code "dance" makes the Zombies move somewhat faster than usual, so typing dance until you see the Zombies go at their speed limit is a partial advantage.
 * It is never explained how the cardboard cut-outs attack the zombies since they are only cut-outs. (although, Crazy Dave did say that he made them so there is a possibility that Crazy Dave used something to make the cut-outs move and attack the zombies). Perhaps it is the Magic Taco obtained during Level 4-4 that could have caused it.
 * It is unknown who's brains are there at the place of the lawnmowers.