Corridor 7 (subtitled Alien Invasion) is a game by Capstone Software, released in March 1994. It was based on the Wolfenstein 3D engine, and featured such alterations as shading, different ammo for different weapons and visors for particularly dark levels.
Some of the graphics were used in select Wolfenstein 3D mods, though less so than those of Blake Stone and DOOM. Andy Nonymous' Corridor 7: Alien Wolf uses the game's atmosphere quite well. The music from the game has been more widely used, most notably in Project: Eisenritter.
A sequel, Corridor 8, was planned, but ultimately canceled when Capstone Software went bankrupt.