Doom 2D

Doom 2D is a fan-made DOS-based freeware side-scrolling video game based upon Doom. Doom 2D is essentially the original Doom translated into a two-dimensional arcade or console-like shooter, comparable to the original Duke Nukem. The player resumes their role as Doomguy, who must do battle with various hell-spawn.

Originally appearing entirely in Russian, eventually a partially-translated English version appeared and both are still available for free on the Internet.

Story
The story of Doom 2D is presumably the same as that of the original Doom, which contained very few story details in-game. Doom 2D has even less in-game plot developments than this, simplifying the already simple objectives found in Doom games.

Gameplay
Gameplay utilizes a simple and customizable set of keys to navigate a 2D environment and defeat and pass monsters. The game also offers two-player cooperative-play or deathmatch options, which can be played using different keys on a single keyboard.

Visual styles and creatures
All creatures from the original Doom appear in Doom 2D, as Doom 2D utilizes the monster sprites (and others, such as object sprites) ripped from the original Doom. The difference, of course, is that in Doom 2D the creatures are mostly seen from the side (as opposed to the front, as it is in Doom) due to the different perspective. Most of the game's foreground and background elements were as well extracted from Doom, as were the sound effects.