Technically this can be achieved to varying degrees of success depending on your target platform by exploiting the OpenBrowser() function. On modern Windows computers it won't work very well due to the security of all browsers. On iPhone, you can open any installed app that has implemented the requested URL hook (but there's no good way to check if the user has the requested app installed before attempting to launch it).
For instance, to launch Instagram on an iPhone and put it in Camera mode so the user can take a picture, you can call:
Quote: "OpenBrowser("instagram://camera")"
(You'd have to be in Tier 2 to actually write an AppGameKit program to support such protocol hooks itself so one AppGameKit app could launch another AppGameKit app).
To attempt opening Notepad on Windows, you could use:
Quote: "OpenBrowser("file:///c:/Windows/System32/Notepad.exe")"
This will launch the default browser and try to open the EXE. In modern Internet Explorer you'll get multiple warnings and prompts before being able to run it, while other browsers will simply try and save it as a copy. So this method is definitely not advised.
