1. Introduction of the game:
Farm Heroes Saga is a match-three puzzle game developed by King, the creators of Candy Crush Saga. This vibrant and addictive game invites players to switch and match various cropsies to save them from Rancid the Raccoon, who is looking to spoil the precious farm lands. Set against a backdrop of colorful fields and based on a farm theme, players go through levels to collect different types of cropsies by aligning them in rows of three or more.

2. All characters and levels of the game:
The game features a myriad of charming characters that include the adorable Farm Heroes themselves. Players will meet a variety of friendly farm animals and other figures like apples, carrots, water droplets, and suns, each with their unique personalities and quirks. As for the levels, the game boasts hundreds of stages that increase in difficulty as players progress. Each level presents its own challenges with varying objectives, from collecting a certain number of a specific cropsie to achieving points within a limited number of moves.

3. What attracts users most to the game:
Users are often drawn to the game's colorful graphics, straightforward but engaging gameplay, and the sense of progression and achievement felt when advancing through the levels. The game also frequently updates with new levels and events, which keeps the intrigue alive. Additionally, the social aspect, where you can compete against friends or help each other, adds another layer of engagement.

4. Why it is popular:
Farm Heroes Saga's popularity can be attributed to its simple yet strategic gameplay, the satisfaction of solving puzzles, and the rewarding feeling of leveling up and defeating the game's antagonist, Rancid the Raccoon. The game’s appeal to a wide audience, the ability to play in short bursts, and its availability on multiple platforms including mobile devices have also contributed greatly to its popularity.

5. When the game was released and how many versions are currently available:
Farm Heroes Saga was first released on April 10, 2013. Over the years, the game has gone through several updates and iterations, with new versions regularly released to keep the game fresh and exciting. These include the main game across various platforms, as well as occasional spin-offs or special versions tied to events or seasons.

6. The most difficult part of the game:
Some users find that the most difficult aspect of Farm Heroes Saga is the higher level challenges that require meticulous planning and strategy. These levels often introduce complex gameplay mechanics, like flowers, ice, or eggs, and limited moves to achieve objectives, which can be quite challenging to navigate.

7. Strengths and weaknesses of the game:
One of the game's strengths is its ability to blend simple gameplay mechanics with deeper strategic elements, which can appeal to casual gamers and puzzle enthusiasts alike. The weaknesses may include a reliance on in-app purchases for additional lives or boosters, which can become a hurdle for players who wish to progress without spending money.

8. What other games have been developed by the same developer:
King, the developer of Farm Heroes Saga, is well-known for creating a host of popular games in the casual gaming market. Some of their most notable titles include Candy Crush Saga, Bubble Witch Saga, Pet Rescue Saga, and many more, offering a variety of gaming experiences that often focus on puzzle or matching mechanics.