george++ wrote: "Given the abilities of the AppGameKit, could you describe what would be the biggest project for a programmer? I still don't have a clear picture of AGK's abilities in network programming."
I don't think I fully understand your question: AppGameKit has TCPsockets, that's about everything you will ever need for most games. Only downside is that it doesn't support UDP sockets. But I think, if you're getting in trouble because TCP doesn't suit your need anymore and you really need UDP, you will probably use another engine already. (because of other limitations, graphic wise)
The example of Clash Royale (which isn't an MMO as far as I can see, it's more of a dueling game) will perfectly work on TCP.
Only if you're writing a game that needs REALLY fast data transfer (MMOFPS for example), you'll need UDP and AppGameKit won't suffice.
Mathias