1. Introduction of the game:
Pokémon Go is an innovative mobile game that merges the virtual world with the real one through augmented reality. Developed and published by Niantic, Inc. in collaboration with Nintendo and The Pokémon Company, the game encourages players to explore their surroundings to discover, capture, train, and battle with a wide variety of Pokémon characters.

2. All characters and levels of the game:
Pokémon Go features a plethora of Pokémon characters, ranging from the classic favorites of the original 151 to the ever-expanding roster that includes species from various generations of the Pokémon universe. There are no traditional "levels" in the game. Instead, players level up their Trainer by catching Pokémon, battling at Gyms, participating in Raids, and completing in-game quests. The game continually grows with updates that introduce new Pokémon and special events that offer exclusive gameplay experiences.

3. What attracts users most to the game:
Users are predominantly attracted to Pokémon Go due to its unique blend of real-world exploration and the nostalgia and joy induced by catching Pokémon—something many have fantasized about since childhood. Additionally, the social aspects of the game, including battling in Gyms, cooperative Raid Battles, and Trading Pokémon with friends, contribute to its allure.

4. Why it is popular:
Pokémon Go's popularity can be attributed to its novel use of augmented reality technology, which offers a truly immersive experience, alongside its massive fan base from the existing Pokémon franchise. The game's social features foster community interaction and physical activity, resonating well with both gamers and casual players who are looking for an entertaining reason to get outdoors and explore.

5. The most difficult part of the game:
One of the most challenging aspects of Pokémon Go is completing the Pokédex, as it requires players to capture some extremely rare and regional Pokémon. High-level Raid Battles also present significant difficulty, often requiring coordination with other players to succeed.

6. Strengths and weaknesses of the game:
Strengths of Pokémon Go include its ability to encourage physical activity and its strong community engagement. The game is accessible to a wide range of users, with free-to-play elements. Weaknesses might include its heavy reliance on location, limiting playability for those in less populated areas, and the potential for repetitive gameplay. Additionally, because it uses GPS and augmented reality, it can be demanding on a device's battery life.

7. What other games have been developed by the same developer:
Niantic, Inc., the developer of Pokémon Go, has also developed other augmented reality games that encourage physical movement and exploration, such as Ingress and Harry Potter: Wizards Unite. Their catalogue continues to expand as they focus on building out more real-world interactive experiences for mobile users.