Expert Mode

Expert mode is a game mode, there is not much to say here.

Description
Play your favourite levels again, now, you get more stronger plants, yet, zombies are 3X tougher

New plants

 * Supercharged Peashooter
 * Supercharged Sunflower
 * Supercharged Cherry Bomb
 * Supercharged Wall-nut
 * Supercharged Potato Mine
 * Supercharged Snow Pea
 * Supercharged Chomper
 * Supercharged Repeater