Ironically Wolfenstein 3D, a title widely thought to have later popularized the first-person shooter genre, featured a secret level based on Pac-Man and early in its development designer Tom Hall had suggested a name along the lines of "3-Demon" before id Software decided to do a semi-remake of the once popular Apple II game Castle Wolfenstein.
The player wanders through a 3-D maze, eating pellets and avoiding red ghosts. Eating a power pellet turns the ghosts green and gives the player the ability to eat them for extra points. It is a notable example of an early video game told from a first-person perspective. Similar to Pac-Man, the game had an increasing difficulty for each level completed. However, unlike Pac-Man, the player wasn't required to eat all the pellets, but an increasing percentage for every level completed. The player could gain bonus points by eating extra pellets over the level requirement and skip to the next level at any point (which could be used to avoid ghosts when trapped), being automatically advanced upon eating all pellets in the level.