Doom free Mac Game

While traversing the levels, the player must fight a variety of enemies, including demons and possessed undead humans, while managing supplies of ammunition, health, and armor. Enemies often appear in large groups, and the game features five difficulty levels which increase the quantity and damage done by enemies, with enemies respawning upon death and moving faster than normal on the hardest difficulty setting. The monsters have very simple behavior, consisting of either moving toward their opponent, or attacking by throwing fireballs, biting, and clawing. They will fight each other if one monster is accidentally harmed by another, though most monsters are not harmed by other monsters of the same kind. Levels can also include pits of toxic waste, ceilings that lower and crush anything below them, and locked doors which require a keycard, skull-shaped key device, or a remote switch to be opened. The player can find weapons and ammunition placed in the levels or can collect them from dead enemies; weapons include a pistol, a chainsaw, a plasma rifle, and the BFG 9000, among others. The levels also feature power-ups such as items that give health or armor points, increase the player character's maximum ammunition or health, fill out the automap, give partial invisibility, or allow the player to survive in toxic waste. There are also items which apply time-limited effects such as invulnerability or a berserker status.

In addition to the main single-player game mode, Doom features two multiplayer modes playable over a local network: "cooperative", in which two to four players team up to play through the main game, and "deathmatch", in which two to four players play against each other. Online multiplayer was later made available a year after launch through the DWANGO service. Doom also contains cheat codes that allow the player to be invulnerable, obtain every weapon, be able to instantly kill every monster in a particular level, and several other abilities.

Plot

Doom is divided into three episodes: "Knee-Deep in the Dead", "The Shores of Hell", and "Inferno". A fourth episode, "Thy Flesh Consumed", was added in an expanded version of the game, The Ultimate Doom. The game itself contains very few plot elements, with the minimal story instead given in the instruction manual and short text segues between episodes.

In the future, the player character (an unnamed space marine) has been punitively posted to Mars after assaulting a superior officer, who ordered his unit to fire on civilians. The space marines act as security for the Union Aerospace Corporation's radioactive waste facilities, which are used by the military to perform secret experiments with teleportation by creating gateways between the two moons of Mars, Phobos and Deimos. Three years later, Deimos disappears entirely and "something fraggin' evil" starts pouring out of the teleporter gateways, killing or possessing all personnel. The Martian marine unit is dispatched to investigate, with the player character left to guard the perimeter with only a pistol while the rest of the group proceeds inside the base and is killed. Being unable to pilot the shuttle off of Phobos by himself, he realizes that the only way to escape is to go inside and fight his way through the complexes of the moon base.