1. Introduction of the game:
Angry Birds Friends is a competitive, social gaming extension of the original Angry Birds franchise. Developed and published by Rovio Entertainment, this game taps into the core mechanics of slingshot action, where players launch colorful birds with distinct abilities at structures to topple pigs ensconced within. Unlike its predecessors, Angry Birds Friends emphasizes multiplayer competition, allowing players to challenge friends and other competitors across the globe in weekly tournaments, ensuring a dynamic and ever-changing gameplay experience.

2. All characters and levels of the game:
The game features a cast of characters familiar to fans of the Angry Birds series, including Red, Chuck, Bomb, Matilda, The Blues (Jim, Jay, and Jake), and Terence, among others, each with unique abilities. The levels in Angry Birds Friends are dynamic and change weekly, aligning with the tournaments that are held. Players are treated to a mix of new and classic levels, designed to test skills and strategies in varying environments.

3. What attracts users most to the game:
Players are attracted to Angry Birds Friends due to its competitive nature and the social aspects of gameplay. The weekly tournaments serve as a strong incentive to return, offering fresh challenges and the chance to outscore friends and other players. The game also retains the charming graphics and humor characteristic of the Angry Birds series, which fuels its broad appeal.

4. Why it is popular:
Angry Birds Friends enjoys popularity because it combines the beloved gameplay of the original Angry Birds titles with a competitive social twist. The ability to compete against friends adds an element of rivalry that is enticing for many. Additionally, constant updates and seasonal events keep the game fresh and engaging, ensuring long-term replayability.

5. The most difficult part of the game:
The most difficult part of Angry Birds Friends can vary from player to player, but it often involves mastering the precise angles and power required to achieve the maximum destruction and the highest scores, especially under the pressure of the tournament setting against skilled opponents.

6. Strengths and weaknesses of the game:
One of the key strengths of Angry Birds Friends is its engaging multiplayer mode, which adds a layer of competitiveness not found in earlier games. The familiar yet challenging gameplay and regular updates are also strong points. On the downside, some users may find the reliance on in-app purchases for power-ups off-putting. Furthermore, the need for a constant internet connection for weekly tournaments could be a hindrance for those with unstable connections.

7. What other games have been developed by the same developer:
Rovio Entertainment, the developer of Angry Birds Friends, has developed an expansive suite of games within the Angry Birds universe, including Angry Birds Classic, Angry Birds 2, Angry Birds Space, Angry Birds Star Wars, and Angry Birds Rio. The developer has also branched out into different genres with games like Bad Piggies, a spin-off that focuses on engineering vehicles for the pigs, and Battle Bay, a real-time multiplayer battle game.