1. Introduction of the Game:
Legends of Runeterra is a thrilling digital card game where creativity, clever strategizing, and tactical execution pave the path to victory. Set in the rich and diverse universe of League of Legends, this free-to-play game developed by Riot Games invites players to craft their own stories using a vast array of cards inspired by the characters and locales of Runeterra.

2. All Characters and Levels of the Game:
Characters in Legends of Runeterra, known as Champions, stem from the various regions of Runeterra such as Demacia, Noxus, Freljord, Piltover & Zaun, Shadow Isles, Ionia, Bilgewater, Targon, Shurima, and Bandle City. Each region offers unique playstyles reflecting its intrinsic lore, and Champions from these regions evolve as they fulfill specific conditions during matches. The game doesn't have levels in the traditional sense but rather ranks that players climb through competitive play.

3. What Attracts Users Most to the Game:
The allure of Legends of Runeterra lies in its deep strategic elements, the capability to make meaningful choices, and the ongoing commitment to a balanced and evolving metagame. The game's regular updates, engaging art, and the familiarity of the League of Legends universe also contribute to its magnetic appeal, drawing in both card game enthusiasts and fans of the lore.

4. Why It Is Popular:
Legends of Runeterra's popularity can be attributed to its user-friendly mechanics, free-to-play model that eschews pay-to-win pitfalls, and a diverse array of strategies that cater to a multitude of playstyles. Additionally, its connection to the well-established franchise of League of Legends provides it with a strong foundational fanbase.

5. When the Game Was Released and How Many Versions Are Currently Available:
Legends of Runeterra was officially released on April 30, 2020. Since its inception, the game has launched multiple expansion sets, featuring new cards and Champions that expand the gameplay and strategic options. The game is constantly updated with balance adjustments and content releases, keeping the player base engaged and the experience fresh.

6. The Most Difficult Part of the Game:
The most challenging aspect of Legends of Runeterra is mastering the intricacies of deck building and the ability to adapt to an ever-changing meta. The depth of possible interactions between cards requires thorough understanding and foresight, making high-level play both challenging and rewarding.

7. Strengths and Weaknesses of the Game:
Strengths of Legends of Runeterra include its rich strategic gameplay, generous reward system, stunning visuals, and the active involvement of the developers to ensure balanced play. However, its weaknesses may reside in the steep learning curve for new players, the potential for overwhelming choices given the breadth of cards, and the occasional dominance of certain decks in the meta.

8. What Other Games Have Been Developed by the Same Developer:
Riot Games, the developer behind Legends of Runeterra, is renowned for creating League of Legends, one of the most played PC games globally. They have also expanded their video game portfolio with other titles like VALORANT, a tactical first-person shooter, and Teamfight Tactics, an auto-battler game. They continue to develop and publish titles that resonate with different segments of the gaming community.