In 1991, Duke Nukem was released by Apogee Software, now known as 3D Realms. Duke Nukem was a 2D platformer that had three episodes where Duke fought his way through a ruined city, a moonbase and in the future to put a stop to Dr. Proton and his army of killer robots. Duke Nukem was followed two years later by Duke Nukem II, that changed up the plot by replacing Dr. Proton with the Rigelatins, an evil alien race. The sequel also improved the graphics, but the core gameplay elements stayed intact.
In this game Duke appears different than he does in later games that we all know him has, in this game Duke has a very bright red face, and just looks much different to the more modern Duke that we are all familiar with today. He also has a less controversial tone than he does in later games.
The game takes place in the year 1997, 6 years into the future from when the game was made. A once respected genius and scientist, Dr. Proton, has taken over earth's largest city with his army of TechBots. The self-proclaimed hero Duke Nukem is hired by the CIA to stop him. Armed with a CIA prototype nuclear pistol and his can-do attitude, Duke is dropped down into the besieged city challenged to find and deal with Dr. Proton. Duke eventually confronts and defeats Dr. Proton. After doing so he uses Dr. Proton's time machine to transport himself back to earth where he receives the key to the city.
Duke Nukem is a 2D side-scrolling platformer with destructible objects which could contain health, weapon upgrades, or inventory items. The game consists of several levels that to complete the player must reach the exit. At the end of the level the player is awarded bonuses for doing such things as destroying all the cameras in a level. The player can earn up to seven 10,000 point bonuses at the end of every level with the exception of the last level. Duke Nukem also contains many collectibles including footballs, soda, balloons, and flags. All of these collectible add to the player's score at the end of a level.
During the code fix stage between version 1.0 and version 2.0 of the game, Apogee found out that a supervillain from the Captain Planet and the Planeteers cartoon was named "Duke Nukem". Thinking it was copyrighted they changed the name of the game to "Duke Nukum". Later, during the development of the sequel ( Duke Nukem II), it was discovered that "Duke Nukem" wasn't copyrighted after all, so Apogee used the original name for all the sequels.