In the game, the player assumes the role of a World War II Allied spy William "B.J." Blazkowicz, as they Escape from the Nazi German prison Castle Wolfenstein, and then carry out a series of crucial missions against the Nazis. The game was released through Apogee in two sets of 3 episodes, using the Apogee model of shareware publishing where the first episode was released for free to drive interest in the rest. It is widely regarded as having helped popularize the first-person shooter genre and establishing the basic run-and-gun archetype for many subsequent games, as well as showcasing the viability at the time of the shareware publishing model. The game is broken up into levels, each of which is a flat plane divided into areas and rooms by a grid-based pattern of walls and doors, all of equal heights. If the player's health falls to zero, they lose one life, and start the level over with a knife, a pistol, and eight bullets. The player begins each episode with three lives, and can gain more by finding extra-life tokens or by earning enough points. in "Escape", Blazkowicz has been captured while trying to find the plans for Operation Eisenfaust and imprisoned in Castle Wolfenstein, from which the player must Escape.