This is a documentation on how to open and re-skin the app:
1. Import the project to Android Studio.
2. You can change the sounds of the keys by going to raw folder and add your sounds in appropriate names.
3. You can change the keys graphics by going to drawable folder and change the keys graphics.
4. Change your admob id by going to the string file and put your id :
<string name="banner_ad_unit_id">put_your_admob_id_here</string>
5. Of Course you can add more keys by going to the activity_main.xml, copy and paste one of the buttons and change its layout_x by adding 55 to the previous layout_x.