1. Introduction of the game:
Welcome to QuizUp, the ultimate trivia challenge that tests your knowledge on a wide range of topics! Whether you're a history buff, a sports enthusiast, or a pop culture junkie, QuizUp is the game for you. Show off your expertise and compete against friends and players from around the world in this exciting and addictive quiz game.

2. All characters and levels of the game:
In QuizUp, there are no specific characters. Instead, players create their own personalized avatars to represent themselves in the game. As for levels, there is a vast variety of topics to choose from, covering everything from geography and science to movies and TV shows. With thousands of topics and questions available, there is always a new challenge awaiting players at every level.

3. What attracts users most to the game:
The most attractive aspect of QuizUp is undoubtedly its extensive selection of topics. Whether players are passionate about music, technology, or even specific TV shows, there is a topic to cater to every interest. Additionally, the competitive nature of the game, where users can challenge friends or engage in global competitions, adds an extra element of excitement and motivation.

4. Why it is popular:
QuizUp has gained immense popularity due to its addictive gameplay and community-driven experience. The ability to play against friends, compare scores, and climb the global leaderboards creates a sense of healthy competition and encourages players to continuously strive for improvement. Furthermore, regular updates and new content keep the game fresh, ensuring players always have new challenges to conquer.

5. When the game was released and how many versions are currently available:
QuizUp was initially released in November 2013 for iOS devices. Since then, it has expanded to other platforms, including Android and web versions. Currently, there are multiple versions of QuizUp available, each continuing to add new features, topics, and improvements based on user feedback.

6. The most difficult part of the game:
One of the most challenging aspects of QuizUp is the sheer breadth of topics available. With thousands of questions spanning numerous subjects, players must possess a broad knowledge base to excel in the game. Additionally, the rapid pace of the quizzes and the pressure of competing against others can make it challenging to correctly answer questions within the time limit.

7. Strengths and weaknesses of the game:
QuizUp's strengths lie in its massive database of questions, diverse range of topics, and its engaging multiplayer feature. The game offers a competitive and social experience that keeps users coming back for more. However, some players may find the difficulty level of certain topics uneven or experience occasional technical issues, which are areas for improvement.

8. What other games have been developed by the same developer:
QuizUp is developed by Plain Vanilla Games, a company known for its focus on trivia-based games. They have also developed other popular games such as QuizDuel and Would You Rather, both of which offer similar trivia-based gameplay experiences.