1. **Introduction of the Game**
"Last Day on Earth: Survival" thrusts players into a post-apocalyptic world where survival is the sole goal. Developed by Kefir Games, this immersive MMORPG places emphasis on resource gathering, crafting, and combat as players fend off hordes of zombies and hostile survivors. The game's compelling mechanics and open-world freedom allow players to build shelters, form alliances, and unravel the dystopian narrative that underpins their struggle to live another day on Earth's harrowing landscape.

2. **All Characters and Levels of the Game**
Players begin as a lone survivor and can customize their character's appearance. As there is no traditional character level system, progress is measured by the player's base development, skills learned, and gear crafted. The game features multiple zones of increasing difficulty, from the relative safety of the home base and surrounding green zones to perilous red zones and secretive bunkers brimming with loot and dangers.

3. **What Attracts Users Most to the Game**
"Last Day on Earth" offers a gripping survival experience that rewards strategic planning and tactical decision-making. The crafting and base-building aspects, combined with the thrill of exploring dangerous areas, resource management, and interaction with other players through raids or clans, make for an engaging gameplay loop. The perpetual threat and unpredictability of the environment keep the stakes high and players deeply invested in their survival journey.

4. **Why It is Popular**
Its popularity can be attributed to the game's challenging survival mechanics, sandbox-style gameplay, and the engaging multiplayer features that allow friends to collaborate or competitors to clash. Regular updates, seasonal events, and the overall survivalist theme resonate with players who enjoy the survival genre, adding to its widespread acclaim.

5. **The Most Difficult Part of the Game**
The most challenging part of the game is often considered to be the high-level areas, such as the infected forest, bunker levels, and the recent additions like the police station or the port. Players must face tougher enemies and carefully manage their resources while dealing with the threat of other survivor raids and the constant need to find food and water.

6. **Strengths and Weaknesses of the Game**
Strengths include its deep crafting system, the satisfaction of building and fortifying a base, and the game's multiplayer component that adds a layer of depth and social interaction. However, some weaknesses are the grindy nature of resource collection, the potential pay-to-win elements introduced through in-app purchases, and the steep learning curve that might deter newcomers.

7. **What Other Games Have Been Developed by the Same Developer**
Kefir Games has also developed other popular titles in the survival genre such as "Frostborn: Coop Survival", which shares a similar aesthetic to "Last Day on Earth" but with a focus on cooperative gameplay, Northern mythology, and a slightly different take on survival mechanics. They are also known for "Grim Soul: Dark Fantasy Survival", which incorporates dark fantasy elements into a survival framework similar to "Last Day on Earth."