I know how they are cracked (http://news.ycombinator.com/item?id=1343066). I was wondering why no one was doing a file compare on the original Myth cracked exe and the one from Steam.
But you're wrong about game exes being packed by release groups. There is nothing to "hide" from other groups. Once you remove the commercial protector (SecureROM, etc.) the rest of the patches are pretty trivial.
The ripping groups had the best crackers, while the ISO groups had the best suppliers. It was normal for Myth to partner with an ISO group to get a game, crack it for them, and then rip the audio/videos and release the 0day version.
This was probably more than just a no-cd crack. Most retail games are protected by some type of packing system (meaning the .code section of PE executable is encrypted on the hard disk and then decrypted once in memory). The cracker has to dump the .code section to the disk once it is unpacked while in memory and then rebuild the executable (hence the ability to put the Myth logo in the file) to run properly (and probably cracking the additional no-cd checks).
So this is could be bad, real bad, since it's a executable that was basically rebuilt from a memory dump, not by a compiler.
But you're wrong about game exes being packed by release groups. There is nothing to "hide" from other groups. Once you remove the commercial protector (SecureROM, etc.) the rest of the patches are pretty trivial.