Plants vs. Zombies 2 is a freemium game, unlike its predecessor, supporting in-app purchasing of coins to use certain power up abilities: Plant Food, a new power-up, allows plants to power up for varying amounts of time. Each plant has its own ability when given Plant Food. Players can complete the whole game without purchasing these abilities, some of which can be earned throughout the game instead of being purchased. Additionally, users can level up their plants using Seed Packets (found in-game or bought with real money) to allow them to permanently enhance their abilities. Players can start an optional tutorial which takes place in front of the player's house. Afterward, the player travels to Ancient Egypt and can win in-game World Keys by completing Day 6 to unlock a series of additional period settings ("worlds"); this required a certain number of stars in earlier updates. Worlds include Jurassic Marsh, Pirate Seas, and Lost City. The Chinese version has five additional worlds, which are Kungfu World, Sky City, Steam Age, Heian Age and Renaissance Age. As players go through levels, they unlock new plants each with advantages and unique boosts.