1. Introduction of the game:
Epic Seven is a visually stunning and immersive mobile turn-based RPG game that brings to life a detailed and enchanting world through its high-quality 2D animation. Developed by South Korean company Smilegate Megaport and Super Creative, the game draws players into an epic adventure filled with a deep storyline, captivating characters, and thrilling battles. It combines traditional role-playing elements with strategic combat and a unique touch-based skill system, allowing for a dynamic gaming experience.

2. All characters and levels of the game:
Epic Seven features an expansive roster of diverse characters, known as Heroes, each with their unique abilities, backgrounds, and designs. Players can collect, upgrade and customize these characters to form their ultimate team. The Heroes are grouped into different classes such as Knight, Warrior, Assassin, Mage, Ranger, and Soul Weaver, catering to various roles in combat. As for the levels, the game contains an array of environments ranging from lush forests to desolate wastelands, each with its array of stages and difficulty settings. Players progress through an ever-evolving storyline, in addition to seasonal events and challenges that offer varying levels of difficulty.

3. What attracts users most to the game:
Players are most attracted to Epic Seven for its captivating anime-style animation, deep strategic gameplay, and the sheer variety of Heroes to collect and develop. Fans of the genre also appreciate the engaging storyline and the regular updates that introduce new content, keeping the game fresh and exciting. The game's community and collaboration aspects, such as guilds and PvP content, also enhance its draw for users.

4. Why it is popular:
Epic Seven's popularity can be attributed to several factors, including its high production quality, attention to detail in character design, and a narrative that keeps players invested. The game's fundamentals, which encourage strategy and customization, along with a fair monetization system that does not overly penalize free-to-play players, contribute to its widespread appeal.

5. When the game was released and how many versions are currently available:
Epic Seven was officially released in August 2018. Since then, the developers have consistently updated the game with new versions, including major and minor patches, to fix issues and introduce new content. However, the game itself remains as a single evolving title rather than having multiple separate versions.

6. The most difficult part of the game:
One of the most challenging aspects of Epic Seven is the endgame content, particularly the Abyss, Raid Labyrinths, and high-level Arena battles, which demand well-thought-out team compositions, high-level gear, and advanced strategic planning.

7. Strengths and weaknesses of the game:
Strengths of Epic Seven include its exceptional art and animation, engaging combat system, and rich storytelling. Regular updates and collaborative events also keep the community active. The primary weakness could be the steep progression curve for new players and the reliance on RNG for obtaining some of the best characters and gear, which can be a source of frustration for those looking for a more straightforward experience.

8. What other games have been developed by the same developer:
Smilegate Megaport, along with Super Creative, has focused significantly on Epic Seven, establishing it as their flagship title. Smilegate, as a larger entity, is also known for its development of other games such as CrossFire, a popular tactical first-person shooter.