1. Introduction of the game:
SimCity BuildIt is a city-building simulation game developed by Electronic Arts (EA) that challenges players to become the mayor of their own city. Players are tasked with planning and managing the various aspects of a growing metropolis, from residential zones to commercial and industrial areas. The game combines strategic planning with real-time resource management to create a dynamic and engaging mobile gaming experience.

2. All characters and levels of the game:
SimCity BuildIt doesn't have characters in the traditional sense; instead, the player acts as the mayor. The game's "characters" are the citizens who populate the city, commonly referred to as "Sims." Level progression is measured by the player's ability to successfully manage the city and meet the needs of the Sims. As the city grows and the population increases, players unlock new buildings, services, and challenges, effectively moving through different levels of city development.

3. What attracts users most to the game:
Players are often attracted to SimCity BuildIt due to its impressive graphics, the satisfaction of planning and watching their cities grow, and the challenge of managing the complex needs of a thriving city. The interactive nature of resource production, trading, and disaster management, along with the constant influx of new content and goals, keeps players engaged and motivated.

4. Why it is popular:
SimCity BuildIt has become popular because it appeals to a broad audience -- from casual mobile gamers to dedicated fans of the SimCity franchise. The game's easy-to-learn mechanics, combined with its depth of strategy, and the allure of building a unique city from the ground up, contribute to its widespread appeal. Additionally, the frequent updates with new features and in-game events help to maintain a strong player base.

5. When the game was released and how many versions are currently available:
SimCity BuildIt was released on October 22, 2014. While the core game remains the same, it has evolved through regular updates that add new content and features. There aren't multiple versions as such, but rather a continually updated and improved single version of the game.

6. The most difficult part of the game:
One of the most difficult aspects of the game is maintaining a balance between the different city services such as power, water, sewage, and public safety, while also managing the city's budget. As the city grows, players face challenges such as traffic congestion, pollution, and disasters, which require careful planning and quick responses to avoid upsetting the Sims and derailing the city's progress.

7. Strengths and weaknesses of the game:
Strengths of SimCity BuildIt include its immersive and realistic city-building experience, high-quality graphics, and complex simulation mechanics that keep players engaged. However, the game's weaknesses may include a perceived emphasis on in-app purchases to speed up progress, which can be frustrating for some players who prefer not to spend money.

8. What other games have been developed by the same developer:
Electronic Arts (EA) is a major developer and publisher in the gaming industry. It is known for a wide variety of titles including "The Sims" series, the various sports games under the "EA Sports" label such as FIFA, Madden NFL, and NHL, as well as popular franchises like "Battlefield," "Need for Speed," and "Plants vs. Zombies."