I can't quite place it, Maybe if I sit in my Gunstar for a while and defend the Frontier againsed Xur and the Ko-Dan Armada. The effect does seem similar, You have a spinning target releasing all its ammo to kill everything in a certain area.
Maybe MNC is a simulation to find the best player of each of six classes, to defend against the Icemen/Hotshot armada... *Hops into his space DeLorean and flies away*