Can my app can be instantiated without the need to launch a game?

Can my Overwolf app can be instantiated without the need to launch a game?

You can manually launch your app from the OW dock (if your index window is not set to game only or background window).
If you want launch it automatically, one way to launch your app without having to launch a game is to launch it via command line argument: overwolf.exe -launchapp [appid]