1. **Introduction of the Game**
Dragon Raja is a captivating mobile role-playing game that combines incredible graphics, engaging storytelling, and interactive gameplay to offer a unique gaming experience. Developed with the industry-leading UE4 engine, this game takes players on an epic journey through a visually stunning world where science fiction meets fantasy. With a narrative based on the famous novel by Jiang Nan, players can immerse themselves in the complex plot and environment where dragons secretly walk among humans.

2. **All Characters and Levels of the Game**
The game features a diverse array of characters each with their own special abilities and backstories. Players can customize their avatars and choose from several classes, including Assassins, Soul Dancers, Gunslingers, Bladesmasters, and more, each providing different styles of play. As for levels, Dragon Raja boasts an open world with varied environments and tasks that range from main story quests to side missions, allowing players to progress and improve their characters throughout the game.

3. **What Attracts Users Most to the Game**
Players are most attracted to Dragon Raja's top-tier graphics, deeply personalized character customization, and engaging real-time combat system. The social aspects of the game, such as forming clubs (guilds) and the interactive in-game societal roles, also enhance the game’s appeal. Furthermore, the regular updates and events keep the game fresh and exciting for returning players.

4. **Why It Is Popular**
Dragon Raja's popularity can be attributed to its cinematic storytelling, freedom of exploration in a semi-open world setting, and the capacity for players to interact and forge their unique paths within the game. Its success is also driven by its mobile platform accessibility, allowing players to dive into this rich narrative and vast world from virtually anywhere.

5. **When the Game Was Released and How Many Versions are Currently Available**
Dragon Raja was released globally on February 27, 2020. Since its release, there have been various updates and patches, but it remains a singular version that evolves over time through updates rather than standalone versions.

6. **The Most Difficult Part of the Game**
One of the most challenging aspects of Dragon Raja is the high-level competitive play, including facing off against tough bosses in dungeons and battling other players in PvP mode. The strategic depth needed for team formations and gear optimization can also prove to be a difficult, but rewarding, element of the game.

7. **Strengths and Weaknesses of the Game**
Strengths of Dragon Raja include its visually impressive graphics, deep customization options, rich narrative, and dynamic combat system. The weaknesses could be its potentially overwhelming options for new players, the need for a strong device to run the game smoothly due to the high-quality graphics, and some players might find in-app purchases necessary for faster progression.

8. **What Other Games Have Been Developed by the Same Developer**
The developer of Dragon Raja, Archosaur Games, is known for creating other mobile games such as Naval Creed: Warships and World of Kings. They specialize in creating expansive game worlds with a focus on mobile MMORPG experiences.