1. Introduction of the game:
Angry Birds Friends is an addictive and entertaining mobile game that brings the classic Angry Birds gameplay to a competitive, social level. Players are propelled into a vibrant world filled with slingshot-wielding birds, villainous pigs, and creative structures to destroy. The objective? To strategically launch birds to demolish the pigs' fortresses and earn the highest scores possible.

2. All characters and levels of the game:
Angry Birds Friends features a diverse cast of characters, each equipped with unique abilities to tackle the levels. The game initially introduces players to the original Angry Birds such as Red, Chuck, Bomb, and Matilda. As players progress, they unlock additional characters like Terence, Stella, and The Blues. With each new level comes fresh challenges and increasingly clever pig forts to topple.

3. What attracts users most to the game:
The competitive and social aspects of Angry Birds Friends make it a standout game. Players can connect with their friends via Facebook to engage in weekly tournaments, comparing scores and aiming for the top spot on the leaderboard. The thrill of challenging friends and vying for bragging rights is a major draw for users, fostering a sense of community and friendly rivalry.

4. Why it is popular:
Angry Birds Friends has gained massive popularity due to its engaging gameplay, charming characters, and regular updates. The game's simplistic yet strategically complex mechanics make it accessible to players of all ages. Additionally, the incorporation of social features and competitive tournaments amplifies the fun and keeps players coming back for more.

5. When the game was released and how many versions are currently available:
Angry Birds Friends was released in May 2012 and is available on various platforms, including iOS, Android, and Facebook. As of now, the game has undergone several updates, introducing new levels, characters, and features to keep the experience fresh for its dedicated player base.

6. The most difficult part of the game:
The most challenging aspect of Angry Birds Friends lies in the increasingly intricate and formidable pig fortresses players encounter as they progress. Players must strategically aim their birds, taking into account the physics of the game, to efficiently eliminate all the pigs while conserving birds to maximize their scores.

7. Strengths and weaknesses of the game:
One major strength of Angry Birds Friends is its addictive and competitive nature, which provides hours of enjoyment. The regular updates and themed tournaments keep the game fresh and exciting. However, some users may find the game's reliance on in-app purchases to unlock certain power-ups or progress faster as a potential weakness.

8. What other games have been developed by the same developer:
The developer behind Angry Birds Friends, Rovio Entertainment, is widely recognized for creating the immensely popular Angry Birds franchise. They have also developed other successful games, including Angry Birds Classic, Angry Birds Rio, Angry Birds Star Wars, and Angry Birds Space, among many others. Rovio's repertoire showcases their creativity and ability to consistently deliver enjoyable gaming experiences.