1. **Introduction of the game**
Flight Pilot Simulator 3D Free offers an immersive experience for those who dream of soaring through the skies. With its cutting-edge graphics and realistic flight physics, players can take to the air in a variety of aircraft, tackling missions that range from simple landings to challenging rescue operations. It's a game that approximates the thrill of piloting, accessible right from your mobile device.

2. **All characters and levels of the game**
While Flight Pilot Simulator 3D Free doesn't feature characters in a traditional sense, the players themselves become the pilots, each with a fleet of different aircraft to control. The levels are diverse, offering players a range of environments and scenarios. These include tranquil countryside flights, bustling city tasks, and emergency situations such as firefighting or search and rescue operations. Each level increases in difficulty, challenging the players' skill and precision.

3. **What attracts users most to the game**
Players are most attracted to Flight Pilot Simulator 3D Free for its realistic 3D graphics, intuitive controls, and the freedom to explore vast open-world maps. The variety of missions keeps gameplay exciting and unpredictable, while the opportunity to unlock and fly different types of aircraft keeps enthusiasts engaged for long hours.

4. **Why it is popular**
The game's popularity can be attributed to its easy-to-learn mechanics which make it accessible to beginners, while still providing challenging scenarios for seasoned gamers. Additionally, its free-to-play model with in-app purchases makes it easy for anyone to start playing without any upfront investment, broadening its appeal.

5. **When the game was released and how many versions are currently available**
Flight Pilot Simulator 3D Free was initially released in May 2015. Due to its popularity, the game has undergone several updates and iterations to improve the user experience, add new content, and refine the flight mechanics. As of now, there have been multiple versions with periodic updates available on both iOS and Android platforms.

6. **The most difficult part of the game**
One of the most difficult aspects of Flight Pilot Simulator 3D Free can be the emergency missions requiring precise timing and control, such as landing on short runways in poor weather conditions or coordinating rescue operations on rugged terrain.

7. **Strengths and weaknesses of the game**
Strengths of Flight Pilot Simulator 3D Free include its captivating 3D graphics, extensive variety of aircraft, and absorbing open-world missions. However, some may find the game's in-app purchases for quicker progression to be a weakness, along with a possible steep learning curve for the more advanced missions.

8. **What other games have been developed by the same developer**
Flight Pilot Simulator 3D Free was developed by Fun Games For Free, a company known for creating engaging mobile games across various genres. Some other popular games developed by them include Sniper 3D: Fun Free Online FPS Shooting Game, War Machines: Tank Battle, and Colorfy: Coloring Book for Adults, among others.