Hey Cascade Games thanks alot for your amazing comments, this definitely encourages us to do more in our work. :D
Answers to your questions
1. How much time did it took
It took around 18 months to build it from the scratch to publishing.
2. Did you did everything for the game
Yes, every element in the game is build from scratch in our studio exclusively.
3. What was the secret behind designing SO many levels
I had a guy to work exclusively on the levels, while I work on the programming.
4. And also target other platforms like pc. And also give time to promotion strategies.(this is very very important)
Sure, this is a very valuable advice. Thank you :D