Doom II is a sequel to the original Doom. The protagonist, a space marine, returns to Earth after saving Mars from demonic threats. He finds that demons have invaded Earth, killing most of its inhabitants or possessing them. His goal is to bring down the force field around the last operational star port to allow humanity's escape.
The gameplay in Doom II is similar to its predecessor, with 3D graphics and 2D sprites for enemies. The player navigates through 3D environments from a first-person view, shooting demons while searching for switches and keys to find the way out. In contrast to the original Doom, which had three episodes, Doom II features one long episode with 30 levels plus two secret levels.
The game introduces a new weapon, the super shotgun, as well as several new demon types with more advanced attacks. These include Heavy Weapon Dudes with chainguns, Revenants that launch homing missiles, and Arch-Viles with highly damaging fire attacks.