Sorry that I am a bit daft in the RB6 series Staga, and especially the GR set.
I think your eluding to a "zoomable" kick bellybutton scope fully auto gun?
GR seemed to have all the fun minus the say, MOHAA FPS guns graphics upfront which is standard in the FPS's.
That, and the lack of weapons made the new patched GR AI almost unbeatable! Course i suck at it.
The choice of superior weapons, (realistic actually) in the RB6 MOD, made the improved AI not a impossible challenge, but a wave of smart AI to battle.
Again, it just rocks.