1. Introduction of the Game:
Plants vs Zombies 2: It's About Time is a widely popular tower defense game developed by PopCap Games and published by Electronic Arts. The game serves as a delightful sequel to the original Plants vs Zombies and invites players to dive into an action-packed adventure where they defend their garden against a zombie invasion using an arsenal of plants.

2. All Characters and Levels of the Game:
The game boasts a rich cast of characters, including an array of plant defenders such as the Peashooter, Sunflower, Cherry Bomb, and new additions like the Bonk Choy and Lightning Reed. The zombies are equally diverse, with a variety of undead antagonists challenging players at every turn, such as the Jetpack Zombie and the Pirate Captain Zombie. Plants vs Zombies 2 is structured into different worlds set across various epochs, spanning Ancient Egypt, the Pirate Seas, the Wild West, and futuristic settings, among others, each featuring unique levels that offer increasing challenges and gameplay variations.

3. What Attracts Users Most to the Game:
Players are drawn to Plants vs Zombies 2 for its charming graphics, quirky humor, and engaging gameplay that combines strategy with rapid real-time action. The ability to collect and cultivate an ever-growing garden of unique plants, each with special abilities, along with the brain-teasing challenges in various historical-themed levels, makes for an immersive and enjoyable experience.

4. Why It Is Popular:
Plants vs Zombies 2 has gained immense popularity due to its accessible yet deep gameplay mechanics, pleasing aesthetic, consistent updates, and an excellent balance between free content and in-app purchases. The familiarity of the original game coupled with fresh elements and the introduction of new plants and zombies have kept players hooked and helped maintain its popularity.

5. When the Game Was Released and How Many Versions Are Currently Available:
Plants vs Zombies 2 was first released on August 15, 2013, for iOS devices, with subsequent releases on other platforms. Over the years, the game has received multiple updates and expansions, constantly introducing new worlds and characters, and as of my knowledge cutoff in March 2023, it still receives support from the developers.

6. The Most Difficult Part of the Game:
One of the most difficult aspects of Plants vs Zombies 2 can be mastering the later levels where the zombies come with advanced abilities and the player must carefully plan and execute strategies with limited resources. Also, the game's endless zones and challenges such as the Pyramid of Doom and the Temple of Bloom can be especially tough to conquer.

7. Strengths and Weaknesses of the Game:
Strengths of Plants vs Zombies 2 include its engaging strategy gameplay, wide variety of plants and zombies, vibrant graphics, and regular content updates. However, its weaknesses could be perceived as a reliance on in-app purchases for quicker progression and some players might find late-game levels frustratingly difficult without investing in premium plants or power-ups.

8. What Other Games Have Been Developed by the Same Developer:
PopCap Games, the developer behind Plants vs Zombies 2, is also known for developing other hit titles such as Bejeweled, Peggle, and the original Plants vs Zombies. These games, like Plants vs Zombies 2, are characterized by their accessibility, colorful graphics, and engaging gameplay, making PopCap Games a beloved name in the casual gaming market.