Thread:Clownfishten/@comment-26832349-20150802013916/@comment-24453214-20150808164201

The way the game is built, there's very little information that's truly server-side-only. This is so the client can continue to run if it loses contact with the server briefly.

The major sticking point is the combat mechanics. The client determines the results of each combat round independent of the server, so it doesn't have to wait for a server reply. But that opens the game up to someone cheating with a hacked client, so to prevent that, the server also works out the results itself. If the two results don't match, the server boots you out of the battle and disconnects. So a third-party server would have to either a) exactly replicate the client's combat algorithms, or b) blindly accept the client's results and open the door to cheating.