Huh I didn’t think flash clients would still be able be used, though it makes sense since the rest of the game will most likely be untouched; the server in C++, and the Ruby/Python for misc. code. Good to hear that bots would be unaffected! I’ll have to think of some way to force the Unity player then… hell wouldn’t a server side stored checksum work, where you validate the client’s code with it?
An easy way to implement patching would be a game launcher, similar to any game hub or log in page. Titles such as League of Legends, Minecraft, Battle`net, Steam, etc. come to mind. Delete the old client, replace the new one. It is possible for the tech-savy hackers, the ones who actually know programming, to update their clients, but for the general masses, hack clients would become obsolete.