Doctor Klausener is the mastermind behind the events of the trilogy. A former Untersturmführer and Mad Scientist with delusions of power, Klausener conducted twisted human experiments and built a revolutionary machine in a failed attempt to create a generation of Super Soldiers. Several years after the end of the war, the old and crippled Klausener leads a Fourth Reich conspiracy to release his subjects from the now-abandoned secret facility, sacrificing mercenaries and their backup team to achieve his goals. Unleashing the undead army on war-torn Yugoslavia, Klausener's machinations force NATO to consider nuking the area with thousands of people still inside to save the rest of Europe. In the end, Klausener plans on replicating his machine in modern day.
Brigadeführer Götz is the cold-blooded leader of the undead army, lacking the animalistic savagery of his fellow zombies and retaining his strategic nature after his transformation. A known camp commandant involved with Klausener and his experiments, Götz poses as the sole survivor of the project while his soldiers quietly assassinate the mercenaries before launching an attack to kill the remaining men but keeping one of them alive in constant agony, linking him to the machine to expand the electromagnetic field and allow his soldiers to rampage further. Starting his crusade by wiping out the soldiers that arrived to investigate the facility, Götz and his army slaughter countless soldiers and civilians across Yugoslavia, children included, going as far as to decorate his lair with the corpses of his victims and running some experiments of his own.
Standartenführer Strasser is the officer in charge of personally supervising the experiments for Klausener, openly embracing death and enjoying his own cruelty. Strasser treats his own men as guinea pigs in many trials of the Supersoldier program—which involves burning out neural pathways until their heads potentially explode—casually dismissing their brutal deaths while turning penal conscripts and other victims into zombified attack dogs for the Nazis, even setting them on POWs to slaughter them with impunity in his own Gladiator Games. Uncaring towards the soldiers under his command, Strasser simply leaves them to die to give him enough time to flee on his own after recklessly releasing the zombies.
Nightmare Retardant: The cackling witch-like nazi in Black Sun, who is out of place among stoic stab-happy ghosts.
Similarly the Nazi ghosts, despite being genuinely scary and unstoppable killers almost entirely obscured by shadow in the first movie (which helped hide their rather lackluster makeup quite effectively) and shown only in glimpses after about halfway through the movie to build genuine tension, have devolved to gibbering, drooling zombies by the sequel, and are immoderately thrown at the audience from the start in full light and without any tension or buildup, thus making them far less threatening and far less scary.
For the videogame:
Game-Breaker: Especially on harder difficulties, the only way to make your colony sustainable is to build a SPEW (recycling center) and as many residential units as possible. Each residential unit in conjunction with the SPEW produces a resource called Multi Purpose Goo (MPG), which can substitute for any other resource. This is critical because your mines are finite, and most buildings consume resources every turn. Without MPG or Nanotechnology (which takes much longer to reach), it's just a matter of time before your factories, agridomes, and life support shut down for lack of resources.
Genius Bonus: Some audio that can be heard on the cinematics are actual NASA communications, including the launch of Mercury-Atlas 6 and Neil Armstrong's famous "One small step for a man...".