Gameguard is not used here.
Here's some info I've gathered overtime.
Xigncode.log uses CheckDebuggerPresent and IsDebuggerPresent to check if any debuggers are being used.
xxd.xem runs in game, probably scanning for memory edits, etc.
xsg32.exe and xm.exe show the error of application once hack is detected.
Rather there's xigncode within suddenattack.exe, i don't know. But this should be give you some knowledge you didn't have before.