Here I will post some idead about how could be a mayan/aztec world based.
WARNING!: Those are just IDEAS, is not something official.
The Main Theme could be something like this: https://www.youtube.com/watch?v=Smx_2U6I5_A
This could be the Select your seeds theme: https://www.youtube.com/watch?v=6vhykMhdZQE
Those are some plants can could be here, is unfinished so you can help here.
1. Umbrella Leaf.
3. Cocoa Bean. I don't know what could be do.
6. Pitcher Plant. Creates an acid puddle that slow down the zombies and do heavy damage, then the acid puddle makes the tile unable to be planted and you have to wait until that the tile is regenerate, like with the Doom-shroom.
7. Venus Flytrap. Acts like his PvZO counterpart.
The main variants zombies could be named either "mayan zombies" or "native zombies", I don't know.
1. Mayan/Native Zombie. The basic variant.
2. Conehead Mayan/Native. The conehead variant.
3. Buckethead Mayan/Native. The buckethead variant.
4. Flag Mayan/Native Zombie. The flag variant.
5. Plumed Archer Zombie. A weaker version of the Catapult Zombie, and also can't crush plants. Always target the backmost plant in his lane. Weakness: Umbrella Leaf. Speed: Stiff. Toughness: Hardened.
6. Jaguar Warrior Zombie. A tough zombie that don't eat plants, instead he slices the plants with his macana. Speed: Hungry. Toughness: Hardened.
7. Turkey Wrangler Zombie/ Zombie with Macaws. I have two ideas for a zombie with animals. The first one is a sort of Turkey Wrangler Zombie, but this one release Turkeys Zombies one by one and in his lane. He stops in every tile to release a Turkey Zombie. Speed: Basic. Toughness: Dense. The other idea that I have is a Zombie with Macaws, this one release one Macaw Zombie that fly over the plants. Speed: Basic. Toughness: Dense.
8. Turkey Zombie/Macaw Zombie. The Turkey Zombie can float over the plants, and can be attacked with any plant. Speed: Hungry. Toughness: Average. The Macaw Zombie will always fly over the plants, and only Cactus and Homing Thistle can attack him. Blover and Hurrikale also can fly away the Macaws Zombies. Speed: Speedy. Toughness: Fragile.
9. Shaman Zombie. I have two ideas for this zombie. In the first one will acts like the Tomb Raiser Zombie, but instead of raise tombstones will throw skulls that summons a random zombie of this world, even Gargantuars! The only zombies that can't summons is another Shaman Zombie and the Turkey Zombie/Macaw Zombie by themselves. The Gargantuars have a low chance of being summoning. The other idea is that will convert any zombie in a range of 3X3 in a random zombie of this world, even Gargantuars! This is, can upgrade a Basic Mayan/Native Zombie into a Gargantuar, or downgrade a Buckethead Mayan/Native into a basic one. The chances of upgrade any zombie into a Gargantuar is very low. Speed: Creeper. Toughness: Dense.
10. Conquistador Zombie. A mounted zombie with a lot of health! The plants attack either the horse or the rider first depending of the type of plant. Peashooter plants will attack the horse first, while that the lobbed plants will attack the rider first. Plants with AOE can attack both rider and horse. If one of the zombies is defeated first the other one will continue. His armours can be stealed by the Magnet-shroom. Speed: Hungry. Conquistador Zombie toughness: Machined. Horse Zombie toughness: Hardened.
11. Mayan/Native Gargantuar. The Gargantuar variant.
12. Imp Alux. The Imp variant.