I have just released a new version of the Android app that adds the fifth gamebook in the series – Trail of the Wolf! You can download it from Google Play Store.
I plan to release one book each month from now so that the whole series is completed just before Christmas. Stay tuned.
Enjoy the new book and let me know on the Project Aon forum if you encounter any problems, I will fix them ASAP.
Good luck and have fun!