1. Introduction of the game:
Last Empire-War Z is a mobile strategy game that immerses players in a world overrun by zombies. It combines base-building, resource management, and tactical combat as you struggle to survive and thrive amidst the chaos of a post-apocalyptic landscape. Players must fortify their bases, train an army, and forge alliances with others to ward off the relentless hordes of the undead and rival factions.

2. All characters and levels of the game:
In Last Empire-War Z, characters often comprise various military units, each with their unique strengths and abilities. These include infantry, ranged fighters, and heavy units, as well as specialized zombie-killing heroes that players can recruit and upgrade. As for levels, the game typically involves progressing through increasingly difficult stages of base development and combat, where players can level up their command center, expand their territory, and unlock advanced technologies and units.

3. What attracts users most to the game:
Users are drawn to Last Empire-War Z by its engaging combination of survival strategy and social interaction. The thrill of battling waves of zombies, the strategic depth in building and upgrading your base, and the camaraderie found in alliance teamwork provide a multifaceted experience. Additionally, the constant update of events and challenges keep the game exciting and fresh for the players.

4. Why it is popular:
The popularity of Last Empire-War Z can be attributed to its immersive post-apocalyptic setting, its engaging gameplay mechanics, and its social aspects. The game taps into the widespread fascination with zombie apocalypses, allowing players to play out their survival fantasies. Its complex strategy elements appeal to those who enjoy detailed management sims, while the alliance system encourages community building within the game.

5. When the game was released and how many versions are currently available:
Last Empire-War Z was released in 2015. Since its release, the game has been updated frequently with new features, events, and improvements. It is difficult to specify the number of versions as the game is continually evolving, with updates effectively functioning as new versions to keep the game engaging for the players.

6. The most difficult part of the game:
The most challenging aspect of Last Empire-War Z often lies in the PvP (Player vs. Player) battles where strategy and alliance coordination become critical. Players must defend their bases against well-coordinated attacks from other players while also mounting their assaults. Balancing resource management, base defense, and offensive tactics in a live multiplayer environment can be quite demanding.

7. Strengths and weaknesses of the game:
Strengths of Last Empire-War Z include its in-depth strategic gameplay, compelling post-apocalyptic theme, and strong community engagement through alliances. However, its weaknesses may include the potential for pay-to-win scenarios where players can purchase advantages, which might deter some from engaging with the game fully. Additionally, the complexity of the game might overwhelm newcomers who are not accustomed to strategy-heavy games.

8. What other games have been developed by the same developer:
Last Empire-War Z is developed by IM30 TECHNOLOGY LIMITED, which is also known for other strategy titles such as "Rise of Empire," "Z War," and "Age of Z." These games similarly involve strategic management and warfare, often with a focus on survival in hostile environments.