Valkyrie Laboratory is the fourth released Zombie Mode map sets within a large underground test facility. It is available in most versions:
- Valkyrie Lab (Most versions).
- Valkyrie Base (Vietnam).
No one has heard anything about survivors from Venice. Recent intel suggests that the horde is moving towards an underground base. The previous invasion must have only been the beginning. Global Risk forces identified the underground location as Valkyrie Laboratory, which no one knows its purpose.
Global Risk is planning a major campaign, but they need more information. A squad was dispatched to the base. Once inside, the squad saw what was being planned and the potential destruction of mankind. Moments later, the undercover mission was exposed and now must do everything they can to escape with these information.~ Crossfire Vietnam's ingame description.
Soldiers start off in a wide room with various large doors serving as zombies spawns during the whole map. Few SMGs can be picked up by soldiers. There are two supply stations in every sectors of the laboratory, along with four TH-Grenades as well. The first room is quite short and easy, however mutants show up quite early.
At the eighth wave, the first gate opens with a short hallway leading to the Chaos Research Room, a big liquid filled tube with Chaos resting in it. Fortunately for soldiers, he's completely harmless in this cylinder. This sector contains usual zombies, ghosts and now Dreads. Another simple section, until the next gate opens.
At the thirteenth wave, soldiers will access an extremely large proving ground area and pickup various Rifles. This room throws various zombies, mutants and scorchers. At the nineteenth wave, a tyrant mutant will emerge on the second floor, indicating the last wave in the experiment area. Once defeated, the center gate will open.
At the twentieth wave, the huge floor gate opens and leads to an emergency tunnel. Soldiers will fall in a small pond and will then head over four hypomeds to share with each other. Each waves will contains zombies on either side of the tunnel, never both. There is plenty of room to handle the upcoming hordes of zombies and mutants.
At the twenty-fifth waves, the last area is revealed. Four Pistols, Rifles and MGs crates awaits along with four more hypomeds and TH-Grenades. This section contains sniper spots, fortunately, there is a safe spot beside one of the supply station. The later waves throw a massive amount of zombies at the same time, being a real endurance test.
- Main article: Heraklops.
The final gate will open at the far back of the courtyard with Heraklops behind it. There's time to deal with the small wave of snipers before he gets out. Doing the luring tactic will highly help once again to make his shouting attack completely harmless. The flat surface, lack of obstacle and minions out of the way, he's as easy as ever.
Using Melee attacks combined with berserk skill, he will go down in no time. Since this is an easy map overall, beside the last few waves, it can be used as a way to collect Heraklops kills instead of doing Unearth. Doing this map in easy difficulty, like any previous maps, a tyrant mutant will appear instead at the final wave.