You're recruited to Special Combat Unit for training. A leading lieutenant walks up to you... "Hey there rookie! Ready to get started? No? Too bad." He drags you into a warehouse where you see the interior to be quite roughed up, with blue grenade paint shells laying around everywhere, as well as some light blue paint. You're led to the center before a grey protogen comes falling through the roof with a chainsaw... "Meet ShellShock! The best protogen training unit you'll ever go up against."