The AppGameKit is a new programming language and compiler for several different platforms. A daunting task to say the least.
They have left out more advanced features for now so they can get the product into our hands sooner, so we can start making games, and they can make some money to stay in business while they continue development. I can't say for certain what advanced features will come, but this version of the AppGameKit is an early step.
Like Mobiius said, you can do anything you want in C++ and still use the AppGameKit commands along with it.