A Marine Special Forces convoy is blown out of the sky while heading into the research center for a classified mission. Adrian Shepherd survives and heads into the center to complete the grisly job. In this add-on to one of the truly great creations of computer gaming, players battle more of the wayward biological experiments running rampant through the wrecked center. Shepherd will pick up some help along the way because soldiers can be recruited to perform their specialties in crucial situations. The medic will provide inoculations to heal ailing team members.
Engineers fire up torches to cut through sealed doors.
Scientists and guards will open security doors, and marksmen will help blast through waves of enemies. Unfortunately, it's tough to keep them alive because they rush headlong into danger. But when one team falls by the wayside, another team awaits recruitment ahead. Xen, where Shepherd is transported occasionally courtesy of a weapon called the displacer. There are several new weapons and enemies, and some great scenes in this short but satisfying adventure.