Players use melee attacks, firearms and explosives to fight enemies, and may run, jump and occasionally swim to navigate through the locations. Melee attacks can be used to silently take down enemies without being detected. Alternatively, players can ambush enemies, which will result in an intense firefight between the two parties. Enemy types vary; standard Nazi human soldiers, which vary in strength, robot-like characters known as Supersoldaten (Super Soldiers), giant mechanical dogs known as Panzerhunds, zombie-like Nazi soldiers and civilians known as Shamblers, and vicious dogs are some of the enemies players will encounter.
In combat, a cover system can be used as assistance against enemies. Players have the ability to lean around, over, and under cover, which can be used as a tactical advantage during shootouts and stealth levels. Players have access to a weapon inventory, which allows the player to carry as many weapons as they find. With some of these weapons, players have the ability to dual wield, giving them an advantage over enemies by dealing twice as much damage. The Old Blood adds various weapons that were not featured in The New Order, such as a steel pipe. The steel pipe is one of the biggest additions to the game; it consists of two small steel pipes which can be connected together to make a larger pipe. Both pipe states can be used as a melee attacks (each with their own animations) and in specific circumstances. The two small pipes, called "Pipes" in the weapon inventory, can be used to climb rock walls, and the large pipe, called "Pipe" in the inventory, is used to break open weak environmental surfaces. The game gives players a wide variety of weapon options—they can be found on the ground, retrieved from dead enemies, or removed from their stationary position and carried around. Weapon ammunition must be manually retrieved from the ground or from dead enemies.
As with The New Order, players can complete "Perks"; each Perk has a task the player can complete. Perks encourage the player to change their play style on the fly; collecting "helmets", getting silent kills, killing specific enemies a select number of times, getting a set number of kills with a specific weapon, and getting kills via explosives are some of the objectives. Once a Perk's task is complete, the player unlocks a bonus, such as more overall health or armor, more ammunition for a certain weapon, or the ability to gain health after a silent takedown. Various collectibles are also scattered throughout the levels; concept art, character models and bios, notes, which tell small side stories of the game, and gold bars are some of the collectibles.
Other modes in the game differing from the main chapters are Challenge Arenas and Nightmare Levels. Challenge Arenas unlock as the player progresses through the story and are accessed from the main menu. Being a basic arena battle mode, players fight waves of enemies to obtain a Bronze, Silver, or Gold metal. Nightmare Levels are accessed by finding and interacting with a bed that is hidden in each chapter. There's a hidden easter egg where players can play Wolfenstein 3D; the player moves through pixelated hallways, mostly equipped with just a pistol, fighting Nazi soldiers. The objective is to find a key that unlocks an elevator.
Plot
Wolfenstein: The Old Blood takes place in an alternate history 1946, just prior to the prologue of Wolfenstein: The New Order, with O.S.A. agents William "B.J." Blazkowicz (Brian Bloom) and Richard Wesley (taking up the codename Agent One) on a mission to infiltrate Castle Wolfenstein and obtain a top secret folder containing the location of SS-Oberst-Gruppenführer Wilhelm "Deathshead" Strasse from the castle's commander, Nazi archeologist and Obersturmbannführer Helga von Schabbs. Entering the castle disguised as Schutzstaffel officers, B.J. and Wesley fail to find the folder and are captured by Helga's lieutenant, Sturmbannführer Rudi Jäger, a massive and sadistic dog trainer who feeds captured prisoners to his mechanically augmented canines. While Wesley is dragged away by Rudi for interrogation, B.J. succeeds in escaping the prison cells and fighting his way through the castle. B.J. eventually locates Wesley strapped to an electric chair used by the Nazis for torture. Before B.J. can rescue Wesley, Rudi activates the chair and electrocutes him to death. Jager then feeds Wesley's dead body to his prized albino dog, Greta, and straps B.J. into the chair to interrogate him. B.J. breaks free, injures Rudi, and kills Greta.
Escaping the castle, B.J. travels to the nearby village of Paderborn and meets up with the local German resistance leader, Ludwig Kessler, as well as Kessler's assistant Annette, a young Jewish girl whom Kessler is sheltering from the Nazis. Kessler's tavern is attacked by Nazi forces led by Rudi, wearing an experimental suit of power armor, whom B.J. defeats and kills. B.J., Kessler, and Annette flee via rowboat to the village of Wulfburg, where Helga is conducting an archeological excavation attempting to find a hidden underground vault containing occult knowledge previously possessed by King Otto I.
