1. Introduction of the game:
Crossy Road is a popular mobile game that combines the elements of an endless runner and a retro arcade game. The objective is simple, yet addictive: guide a character through a multitude of obstacles, such as busy roads, treacherous rivers, and moving train tracks, all while aiming to achieve the highest possible score.

2. All characters and levels of the game:
Crossy Road offers a vast array of charming and quirky characters, each with their own unique appearance and characteristics. From the traditional chicken to diverse options like unicorns, dinosaurs, and even the Loch Ness Monster, players can choose their preferred character to maneuver through the game's various levels.

As for levels, the game features a wide range of exciting and challenging environments. Players can navigate through bustling city streets, dense jungles, snowy terrains, and even outer space. Each level presents its own set of obstacles and hazards, ensuring that the gameplay remains captivating and entertaining.

3. What attracts users most to the game:
One of the main elements that captivates users in Crossy Road is its simplicity and accessibility. The intuitive swipe controls make it easy for players of all ages to pick up and play the game. Additionally, the engaging and colorful graphics, coupled with humorous character designs, add an element of charm that appeals to a broad audience.

4. Why it is popular:
Crossy Road's popularity can be attributed to its addictive nature and the constant drive to beat one's high score. The game offers a sense of satisfaction and accomplishment when successfully navigating through a challenging level or surpassing previous records. The constant updates and addition of new characters also keep players engaged and encourage them to keep coming back for more.

5. When the game was released and how many versions are currently available:
Crossy Road was initially released on November 20, 2014. Since then, the game has gained immense popularity, leading to multiple versions being developed and released for both iOS and Android platforms. As of now, numerous versions of Crossy Road are available, including themed editions like Disney Crossy Road, PAC-MAN 256, and Crossy Road Castle.

6. The most difficult part of the game:
The most challenging aspect of Crossy Road lies in its timing and precision. Avoiding oncoming traffic, jumping over fast-moving logs, or timing movements across floating platforms requires quick reflexes and a keen eye for detail. As players progress further into the game, the levels become progressively more difficult and demanding, adding to the overall appeal and longevity of the gameplay.

7. Strengths and weaknesses of the game:
One of the major strengths of Crossy Road is its addictive and simple gameplay, allowing players to enjoy quick sessions or longer gaming sessions. The vast variety of characters and levels also provide a great amount of content and replay value. However, some users may find the occasional reliance on advertisements or in-app purchases as a minor weakness of the game.

8. What other games have been developed by the same developer:
Crossy Road was developed by Hipster Whale, an Australian independent game development studio. They have also released other successful titles such as Piffle, a delightful bouncing ball arcade game, and Shooty Skies, an action-packed shoot 'em up set in the world of hipster animals. Hipster Whale's games are known for their charming visuals, addictive gameplay, and accessibility.