First of all, thank you for all your useful comments. We appreciate it.
Finally, the alpha version is ready. In the last 2 months, we changed and improved almost everything in the game, gameplay, UI design, mechanics,...
This version is the alpha version so it's not exactly a finished game and there are known issues, but it is not very different from the final game either. The final version would be bug-free and have a lot more puzzles (100+), and be released in about 45 days for android for free. right now we are making more puzzles :)