Duke Nukem 3D features the adventures of the titular macho Duke Nukem (voiced by Jon St. John), who fights against an alien invasion on Earth. Along with Wolfenstein 3D and Doom, Duke Nukem 3D is considered responsible for popularizing first-person shooters. It was released to major acclaim; reviewers praised the interactivity of the environment, level design, gameplay and unique risqué humor (a mix of pop-culture satire and lampooning of over-the-top Hollywood action heroes). Its lasting appeal and impact on modern video games has led to its being considered one of the most important video games of all time. It was a commercial hit, selling about 3.5 million copies. The game's violent nature, erotic elements and portrayal of women have incited controversy. After fifteen years in development hell, a direct sequel was released called Duke Nukem Forever.