1. **Introduction of the game:**
Sonic Dash is an exhilarating, endless runner game that allows players to take control of Sonic the Hedgehog and his friends as they dash, jump, and spin their way across various terrain, avoiding obstacles, defeating enemies, and collecting rings. Developed by Hardlight and published by SEGA, Sonic Dash leverages the iconic speed and vibrant worlds associated with the Sonic franchise to create an engaging mobile gaming experience.

2. **All characters and levels of the game:**
The game features a plethora of characters from the Sonic universe, including but not limited to Sonic, Tails, Knuckles, and Amy. Each character comes with unique abilities that can be exploited to navigate through the levels more effectively. The levels in Sonic Dash are dynamically generated, offering an ever-changing experience with each new run. Iconic zones like Green Hill and Seaside Hill are reimagined into endless formats, providing familiar yet fresh terrain for players to explore.

3. **What attracts users most to the game:**
Users are most attracted to Sonic Dash due to its fast-paced gameplay, vibrant graphics, and responsive controls that perfectly capture the essence of the Sonic brand. The game's simple yet challenging mechanics also make it easily accessible but hard to master, which keeps players coming back for more. Additionally, the opportunity to play as different characters from the Sonic universe adds variety and replayability.

4. **Why it is popular:**
Its popularity stems from its association with the beloved Sonic franchise, the satisfying sense of speed it provides, and the continuous updates and events that keep the content fresh and engaging. The game's ability to cater to both casual and more dedicated gamers by offering quick play sessions alongside long-term goals contributes to its broad appeal.

5. **The most difficult part of the game:**
One of the most challenging aspects of Sonic Dash is the progressive increase in speed and difficulty as the player advances. The reflexes required become more demanding, making obstacle avoidance and enemy defeat more challenging, which requires players to maintain high levels of concentration and quick reaction times.

6. **Strengths and weaknesses of the game:**
Strengths of Sonic Dash include its engaging gameplay, high replay value, strong brand recognition, and constant content updates that keep the experience fresh. However, weaknesses might include a reliance on in-app purchases for progression, which some players find off-putting, and occasional repetition due to the endless runner format.

7. **What other games have been developed by the same developer:**
Hardlight, the developer behind Sonic Dash, has also been responsible for several other mobile games within the Sonic franchise, including Sonic Dash 2: Sonic Boom and Sonic Forces: Speed Battle. Additionally, Hardlight has ventured outside of the Sonic series to develop games like Crazy Taxi: City Rush and other titles that focus on delivering console-like experiences on mobile platforms.