Play mode
Four Seasons and Climate.
Using weather with differents traits for your game modes and levels. Each season has unique differences and possibilities, some plants might cost more or less and some might be exclusive to a season. The “normal” game mode is likely a representation of spring or summer.
Winter (or Snowing)
Winter features less or no sun, snow might get thick enough to stop you from planting, a snow shovel (or maybe the pot plant) might allow you to clean the ground, though, the snow might make you zombies more slowly, but enables Bobsled zombies to show up.
*Winter related plants might cost less (Winter Melon, Frozen Pea…), while hot related plants (Torchwood, Cherry Bomb, Jalapeno…) cost more, but are also more effective against winter related zombies.
*Frostmint: a “power-up” plant that causes your plants to produce ice based damage for awhile. Unlikely to be usefull in the Winther, but should be available only after defeating a level in that season.
*Christmas Three: Holyday season version of the Marigold, it has a chance of drops “gifts” (chocolate, plants, or others) every once in a while, a alternative, is that when you have one of Christmas Three you always get a gift at the end of the battle. There might have some restrictions to plant it, maybe it can only be planted once per level or maybe it attracts zombies (Santa Zombies or Ballon Zombies).
*Zanta Zombie: Zombie Dressed as Santa Claus, killing it gives you a gift (a new zen garden plant or diamonds, usually). Should appear only in a roof level.
*Ice Skater Zombie: probably one of the most annoying zombies, shows at winter or after the Zomboni Ice Trail, the Ice Skating Blades cause damages to spikeweed and spikerocks, it is a Suicidal Zombie to clean the path to more Zombonis, but still rather annoying.
*Hockey Zombie: The killing combination of the Football Zombie and the Ice Skater Zombie.
*Zombies at general might have winter related accessories.
Spring
Spring features might be just the “regular” season, if not, the may feature is that is much easier to plant in effect, it can be considered a “easy mode”, the plants cost less (specially flower plants) and recharge faster.
*New plants for this season should be Flower based.
*Zombie in love: A zombie killed in the way of a date, features different and more formal clothing and carries flowers and a box of chocolate, when killed you might win the chocolate or a zen garden plant as a reward.
Summer
Summer features might be the “normal” game’s season, if not, the suggested features might be a increase at sun light, but at same time, the heat can damage plants, the heat damage might be avoided with a proper tool, like sprinkles or a irrigator. Heat or Sun based plants become stronger of cheaper. Can be considered a “fast mode”, requiring constant renewing of you plants but with extra sun too pay for it.
*New plants for this season could be desert based.
*Zombies use summer clothes. There is more water-zombies in pool levels.
Autumn
Autumn features a harvest season, there is less sun light than usual, but seed slots recharge faster and/or new plants that become stronger the longer they survive.Also, Halloween and Thanksgiving themes are a good idea.
*A special level or mini-game could feature plating small versions of regular plants that grown and can become bigger than the regular versions, with a proper increase of health and damage, essentially being a level that trains early and fast strategy.
*The holydays zombies can have special attributes or not, but can be just a cosmetic change for comedy purposes
**Halloween Zombies Could have costumes, a potential mini-game could be a invasion of theses specific Zombies and the player inability to determine they true nature. Also, when killed costumes zombies could live the costumes (or part of them, like the mask) behind and the player might have the possibility of collecting them.
**A Costume “power” could be have the face of a plant species and being immune to it’s attacks (the plant won’t attack one of it’s own), unless it is revealed the Zombie true nature (after enough damage or using special plants).
**Blover could remove a zombie costume, or maybe just the “Ghost Zombie” costume
**Plantern could also reveal the costumed zombie true nature, but only inside its light radius.
Other Ideas
Roses: Special defensive/barrier plant that causes damage when zombies try to eat it. Might come in different colors, each with different powers: Pink (for normal), White (Cold), Red (Fire), Yellow (creates small quantities of light?) or other strange colors like Blue (Cold? Or maybe a water based rose) and Black (Nocturnal).
Pumpkin Lantern: Might be a “Triple upgrade”, you need to plant a Pumpkin and Plantern in the same slot in the garden and plant the upgrade in it. Benefits include increased health and the ability to produce small sun quantities.
Zombie Clow Car/ Zombie Clow: When a Zombie Clow Car encounters a barrier (any plant) it starts to “create” Zombies Clows, quickly becoming a problem.
Mini-game/Level/Mode
Giant Garden: Inverting the level with little zombies, both plants and zombies are the same size, but the garden is twice as big.
Zen Challenge: A level/mini-game where you have to defend your Zen garden from a little zombie’s invasion, the challenge is that you are restricted to use only Zen garden plants. Another trait could be that you use money rather than sun to buy plants, so marigolds substitute the sunflowers in this level, and the extra money could be this level’s reward. It might work in regular levels as well.
New Upgrades
Garlic Bomb: When placed in a garlic it will cause it to explode after few seconds creating a big cloud of smelly gas (3x3 size) and causing any zombies in the area to be delayed for few seconds and change to another, similar to the regular garlic. Works against Gigantaur Zombies and Flying Zombies as well. Flavor text should include a joke about how Zombies can’t breath, yet the smell is so terrible that even the undead don’t like it.
Loyal-shroom: to be placed in a scaredy-shroom, still a long-range attacker and still goes in “scared mode” when a zombie tries to it, but is capable to attack zombies in other lanes, as long they are eating another plant, it gives priority to the closer zombies, it can’t attack zombies behind it, but can attack zombies that are in a lane above or below it.
Vulcanic Wood (Torchwood) It is capable to ignite nearly any attack that pass through it’s flame, even from catapults, much like the non-upgrade version, attacks will deal extra damage, but might lose some other special abilities (such as the stun effect of butter).