Editing Doom (1993 video game) (section)

==Gameplay==
[[File:Doom ingame 1.png|thumb|right|Screenshot of the player armed with a chainsaw confronting an undead soldier with a shotgun on a bridge over a chemical waste storage in "Knee-Deep in the Dead"|alt=A hand holding a chainsaw with enemies standing on a path through green liquid]]
''Doom'' is a [[first-person shooter]] presented with [[3D graphics]]. While the environment is shown in a 3D perspective, the enemies and objects are instead 2D [[Sprite (computer graphics)|sprites]] rendered at fixed angles, a technique sometimes referred to as [[2.5D]] graphics or [[billboarding]].<ref name="NotTrue3D"/> In the [[single-player]] campaign mode, the player controls an unnamed [[space marine]]—later unofficially termed "[[Doomguy]]"—through military bases on the [[moons of Mars]] and in [[hell]].<ref name="IGNSEA"/> To finish a level, the player must traverse through labyrinthine areas to reach a marked exit room. Levels are grouped into named episodes, with the final level of each focusing on a [[boss fight]].<ref name="TheGamerGameplay"/>

While traversing the levels, the player must fight a variety of enemies, including [[demon]]s and [[spirit possession|possessed]] [[undead]] humans. Enemies often appear in large groups. The five [[difficulty level]]s adjust the number of enemies and amount of damage they do, with enemies moving and attacking faster than normal on the hardest difficulty setting.<ref name="TheGamerGameplay"/> The monsters have simple behavior: they move toward their opponent if they see or hear them, and attack by biting, clawing, or using magic abilities such as fireballs.<ref name="GSAI"/>

The player must manage supplies of ammunition, [[Health (game terminology)|health]], and armor while traversing the levels. The player can find weapons and ammunition throughout the levels or can collect them from dead enemies, including a pistol, a [[shotgun]], a [[chainsaw]], a [[plasma rifle]], and the [[BFG 9000]]. The player also encounters pits of [[toxic waste]], ceilings that lower and crush objects, and locked doors requiring a collectable [[keycard]] or a remote switch.<ref name="MOD124131"/> [[Power-up]]s include [[Health (game terminology)|health]] or armor points, a mapping computer, [[Invisibility in fiction|partial invisibility]], a [[Hazmat suit|radiation suit]] against toxic waste, invulnerability, or a super-strong melee [[berserker]] status. [[Cheat code]]s allow the player to unlock all weapons, walk through walls, or become invulnerable.<ref name="DoomCheat"/><ref name="DoomExtreme"/>

Two [[multiplayer]] modes are playable over a network: [[Cooperative video game|cooperative]], in which two to four players team up to complete the main campaign, and [[Deathmatch (video games)|deathmatch]], in which two to four players compete to kill the other players' characters as many times as possible.<ref name="DoomVirtualWorlds"/><ref name="MOD148153"/> Multiplayer was initially only playable over local networks, but a four-player [[online multiplayer]] mode was made available one year after launch through the [[DWANGO]] service.<ref name="MOD148153"/><ref name="MOD182184"/>