1. Introduction of the game:
Plants vs Zombies 2 is a highly addictive tower defense game that brings strategic gameplay to fight off hordes of zombies. Developed by PopCap Games, this sequel to the popular Plants vs Zombies franchise takes players on an epic journey through time, battling the undead across different historical eras.

2. All characters and levels of the game:
Plants vs Zombies 2 offers a wide range of characters, both plants, and zombies, each with their unique abilities. From Sunflowers that generate sunlight to Peashooters that shoot peas at the zombies, players can strategically choose the plants to defend their garden. The game features numerous levels set in exciting locations, such as Ancient Egypt, the Wild West, and the Pirate Seas, each with their own set of challenges and zombies.

3. What attracts users most to the game:
The game's captivating gameplay and humorous storyline attract users of all ages. The clever mix of tower defense strategy, cute cartoonish characters, and challenging levels keeps players engaged and entertained. Additionally, the ability to unlock and upgrade new plants and abilities adds a sense of progression and excitement to the gameplay.

4. Why it is popular:
Plants vs Zombies 2 has gained immense popularity due to its engaging gameplay, innovative concept, and charming graphics. The game's addictive nature keeps players coming back for more, ensuring long-term enjoyment. Moreover, the regular updates and addition of new levels and plants by the developers enhance the game's replay value.

5. When the game was released and how many versions are currently available:
Plants vs Zombies 2 was released on July 9, 2013, for iOS and Android platforms. Since its initial release, the game has received several updates and expansions, adding new worlds, levels, and plants to the gameplay. Currently, there is one main version of the game available, regularly updated with fresh content.

6. The most difficult part of the game:
One of the most challenging aspects of Plants vs Zombies 2 is the higher levels, where the zombies become more aggressive and numerous. Balancing limited resources, strategically placing plants, and timing their abilities to counter the overwhelming zombie attacks can make these levels quite difficult to conquer.

7. Strengths and weaknesses of the game:
A major strength of Plants vs Zombies 2 is its intuitive and easy-to-learn gameplay, making it accessible to a broad range of players. The game's colorful and vibrant visuals, coupled with its humorous tone, create a delightful and immersive experience. However, some players may find aspects of the game a bit repetitive, and certain levels may require in-app purchases to progress faster, which can be seen as a weakness.

8. Other games developed by the same developer:
PopCap Games, the developer of Plants vs Zombies 2, has also created a number of other successful games. Some of their notable titles include the original Plants vs Zombies, Bejeweled, Peggle, Zuma's Revenge, and Bookworm Adventures. These games showcase the developer's talent for creating addictive and engaging gameplay experiences.