Scenario 1:

Suppose you create a WordPad type of app using AppGameKit Tier 1 that runs on one platform. The app is able to write a text file and read it back.

Can you transfer the text file to devices of the same platform? If so, how?

Scenario 2:

Suppose you create a WordPad type of app using AppGameKit Tier 1 that runs on two platforms. The app is able to write a text file and read it back.

Can you transfer the text file between devices of different platforms? If so, how?

Since they are separate platforms, would the app on one platform be able to read the text file created by the app on the other platform?

The major issue you have is that all writes within an AppGameKit app are local and sand boxed, which means the file resides in a protected app-centric location. You cannot go and copy that file to some other part of the device as that would violate the safety of a sand box (i.e. you don't want AppGameKit apps writing all over your device now). The solution is to create a central server application that runs on-line 24/7, and which will receive your text data in the form of a network packet. Your server can store the text file locally at the hub, and then send that file out to another other AppGameKit app that might request it. As the same app is used on multiple platforms, it does not matter if it's one device or ten, your file is accessible from the cloud and your AppGameKit app can retrieve it from anywhere at any time. There are one or two threads on how to create a server side app with AppGameKit, but if there is more call for it we will write a tutorial/video on the subject as it's a great mechanism for all sorts of cool app ideas (if you have access to a server plugged into the internet).

AGK currently has no http commands so how can you share your text file with a central server?!!!!

Run an AppGameKit app on a machine that hosts a static IP address. AppGameKit network communication behaves the same across internet IP addresses as those with the computer next to you