I think it's because this one is not GunMetal:
War Transformed by Mad Genius Software, but Gun Metal
by Rage Software that was also released on the OG Xbox in 2002/2003.
While it may feel similar, I think the homophony is accidental.
Apparently there were XBox cheats that involved clocking the analog sticks, but I haven't tried them on PC yet.
Here is the GameFAQs page if you want to try them. https://gamefaqs.gamespot.com/xbox/516236-gun-metal/cheats
If they work that could always be neat, but apart from the joke briefings, I don't think I'll have much use...
Well actually mission skip can help on some of the annoying missions where you're besieged and have to avoid reaching a certain threshold of base destruction.