**1. Introduction of the game:**
One Piece Treasure Cruise is a captivating mobile RPG game based on the popular anime and manga series, One Piece. Developed and published by Bandai Namco Entertainment, the game invites players to relive the adventurous story of Monkey D. Luffy and his crew as they search for the ultimate treasure, the One Piece. With its engaging turn-based combat system, players can experience the thrill of battle while strategically planning their next move to unleash powerful chain attacks.

**2. All characters and levels of the game:**
One Piece Treasure Cruise boasts an extensive roster of characters from the One Piece universe, including Luffy, Zoro, Nami, and many more, each with unique abilities and special moves. Players can recruit and build their own diverse pirate crew from over a thousand characters. The game features multiple levels where players progress through various story arcs and special events, each offering unique challenges and rewards.

**3. What attracts users most to the game:**
Players are most attracted to One Piece Treasure Cruise because of its faithful recreation of the One Piece storyline, the strategic depth of its combat system, and the excitement of collecting and leveling up a wide array of characters. The game's events and crossover promotions also provide fresh content that keeps players engaged, along with the satisfaction of assembling the perfect crew to take on tough adversaries.

**4. Why it is popular:**
The game's popularity stems from its strong source material, with One Piece being one of the most beloved anime and manga series worldwide. Additionally, its easy-to-learn but hard-to-master gameplay appeals to both casual and hardcore gamers. The commitment of the developers to regularly update the game with new features and characters ensures that the community remains active and invested.

**5. When the game was released and how many versions are currently available:**
One Piece Treasure Cruise was originally released in 2014. Over the years, the game has been updated with various versions, maintaining its relevance and introducing new gameplay mechanics. As of now, the game has gone through several major updates and is available globally on both iOS and Android platforms.

**6. The most difficult part of the game:**
The most difficult part of One Piece Treasure Cruise often includes high-level raid bosses and special event challenges where players must devise advanced strategies and have a well-leveled and synergized crew to succeed. These events require a deep understanding of the game's mechanics and can be a tough obstacle for many players.

**7. Strengths and weaknesses of the game:**
One of the game's strengths is its deep character customization and strategic team-building aspects, along with its faithful representation of the One Piece world. However, some players might find the game's gacha system for obtaining new characters to be a weakness, as it can encourage a pay-to-win approach for those seeking the most powerful units. Additionally, for newcomers, the vast number of characters and features might be overwhelming at first.

**8. What other games have been developed by the same developer:**
Bandai Namco Entertainment, the developer behind One Piece Treasure Cruise, is renowned for a multitude of successful titles across various genres. Some other games developed by them include the "Tales of" RPG series, "Tekken," "Soulcalibur," "Dragon Ball Z: Dokkan Battle," and many others that cover various platforms and cater to different gaming audiences.