We can reverse engineer those too, by looking at what the game client expects. Its harder, obviously. But far from impossible.

I started writing my own world of warcraft server about 20 years ago by disassembling the WoW binary. I got to the point that you could log in to the game and run around in a big empty world. I even found a couple mistakes in wow's in-game encryption in the process. Lots of teams have gotten much further than I did. There's whole communities who play wow on private servers.

If we can do that for MMOs, we can do that for just about anything. Especially with LLMs. LLMs are incredibly good at this sort of work.