Apps Make an app over a game

[Baccarda]

Hi everyone!
Is it possible to make an app over a game? For an example if there is game, which is not mine, and i would like to make an app which would allow players who are playing that game to send a short voice message to the opponent which also has the app. If it is possible, then would there be any restrictions for me? Would i need a special permission from game owners?

Thanks in advance, Janis!

 

[bayk]

If game is not yours you can't do anything.
When you build release APK you signed it with your public and private keys. Those keys are define if app yours or not for Android OS. If keys are the same, you will be able to contact with another app and probably do what you need.
Did you consider to contact App owner and propose him your idea? He might give you a keys and even make some API for you.