Doom 64

Doom 64, released on March 31, 1997 for the Nintendo 64, is a sequel to the Doom games, taking place after Final Doom. The game has all new graphics and runs with a modified version of the Doom engine. Doom 64 was released by Midway, in cooperation with id Software. The game will be re-released digitally for the Nintendo Switch, PlayStation 4, Xbox One, and Windows on March 20, 2020. It is also proven to be released on PC as a pre-order bonus for Doom Eternal as a digital copy. The plot focuses on the events following the original Doom/Doom II/Final Doom storyline. An evil entity known as the Mother Demon has survived and brought back the decaying dead creatures you once killed. It is up to you, the Doom Marine, to stop the legions once again.

Doom 64 is one of the games made by many of the original iD employees including John Carmack and John Romero.



Story
Quoted from the Doom 64 manual:

"Your fatigue was enormous, the price for encountering pure evil. Hell was a place no mortal was meant to experience. Stupid military doctors: their tests and treatments, were of little help. In the end, what did it matter - it was all classified and sealed. The nightmares continued. Demons, so many Demons; relentless, pouring through.

Far Away...

The planetary policy was clear. An absolute quarantine was guaranteed by apocalyptic levels of radiation. The empty dark corridors stand motionless, abandoned. The installations sealed.

The Present...

A long forgotten relay satellite barely executing, decayed by years of bombarding neutrons, activates and sends its final message to Earth. The satellites message was horrific, from the planetary void there came energy signatures unlike anything sampled before.

The classified archives are opened. The military episodes code named "DOOM" were not actually completed. A single entity with vast rejuvenation powers, masked by the extreme radiation levels, escaped detection. In its crippled state, it systematically altered decaying dead carnage back into corrupted living tissue.

The mutations are devastating. The Demons have returned even stronger and more vicious than before. As the only experienced survivor of the DOOM episode, your commission is re-activated. Your assignment is clear: MERCILESS EXTERMINATION."

Gameplay developments
Changes were made to the computer Doom engine for use in Doom 64, and gameplay elements were altered. Doom's core gameplay, however remained the same: the exploration of demon-infested corridors, looking for keycards, switches and ultimately the map's exit while surviving deadly traps and ambushes.

Key differences from the computer games in the series include:
 * 32 exclusive new levels
 * New, larger sprites for all enemies, items, weapons and projectiles, created from high-poly rendered models, which were anti-aliased when close to the player to prevent pixelation.
 * New, high-quality sound effects (the same as used in the PlayStation and Saturn versions of Doom).
 * A more horror-based atmosphere than the science fiction-oriented one seen in earlier games, including darker and more foreboding color schemes used to increase a sense of fear in the player.
 * All new textures, scrolling skies, limited room-over-room architecture and more advanced line triggers.
 * Scripted events through macros, such as almost-complete alterations of room structures.
 * Enemies that appear out of thin air after triggering a tripwire or switch.
 * Tripwire booby traps, from darts to homing fireballs.
 * Camera effects
 * More advanced atmospheric colored lighting and effects, such as parallaxing skies, fog, and lightning.
 * A more ambient soundtrack instead of the rock music of past Doom games.
 * More extensive usage of Satanic imagery (pentagrams, inverted crosses, depictions of sacrifice) than the computer version of Doom with differing usages of horror schemes.
 * No commandos, arch-viles, spiderdemons or revenants (perhaps removed due to the limited storage capacity of Nintendo 64 cartridges).
 * The nightmare imp and Mother Demon are introduced as new monsters.
 * The player's viewpoint is from chest level, rather than eye-level, making all objects and characters appear larger in relation to the player.
 * The hell knight and baron of hell can hurt each other with their projectiles, and infight as a result, contrarily to the PC version where there is a hardcoded exception for them.
 * Certain monsters were rebalanced with new behaviors or attack properties (e.g. such as giving the Arachnotron a weaker twin plasma gun instead of a stronger single-barrel one).
 * Re-designed weapons that act more devastating than previous installments of the game series (realistic jostling movements when firing the weapons are also present, including being knocked back a few inches from a fired rocket).

Weapons
All the weapons from the original computer game are present, but redrawn. A new weapon known as the Unmaker or the LaserGun (referenced in-game as "What the !@#%* is this!") has been added. It was first mentioned in the Doom Bible and was planned to be featured in the computer Doom games but never appeared. Its appearance in Doom 64 is its only official appearance, and with the power of three ancient artifacts (known as "Demon Keys" or pentagrams) found in the game, it becomes more powerful by a faster fire rate and a max of three laser beams fired with all three "demon keys". (1st makes Unmaker fire faster, 2nd gives it a second beam, 3rd gives it a third beam).

Weapons include:

Chainsaw, Fist, Pistol, Shotgun, Super Shotgun, Chaingun, Rocket Launcher, Plasma Gun, BFG9000, and Unmaker. (in order of weapon cycling)

The Demon Keys are also a means to clear MAP28: The Absolution: Each teleporter in the map has a symbol representing each key behind them and if the player has the right key, the corresponding teleporter is disabled, making the battle against the horde of demons that teleport in, easier. Also, when killing the Mother Demon, the Unmaker with all "Demon keys" will kill her very quickly.

Levels
Doom 64 featured 32 original levels:

Fun levels:
 * MAP01: Staging Area
 * MAP32: Hectic (super secret level)
 * MAP02: The Terraformer
 * MAP03: Main Engineering
 * MAP04: Holding Area
 * MAP29: Outpost Omega (secret level)
 * MAP05: Tech Center
 * MAP06: Alpha Quadrant
 * MAP07: Research Lab
 * MAP08: Final Outpost
 * MAP09: Even Simpler
 * MAP10: The Bleeding
 * MAP11: Terror Core
 * MAP12: Altar Of Pain
 * MAP30: The Lair (secret level)
 * MAP13: Dark Citadel
 * MAP14: Eye Of The Storm
 * MAP15: Dark Entries
 * MAP16: Blood Keep
 * MAP17: Watch Your Step
 * MAP18: Spawned Fear
 * MAP31: In The Void (secret level)
 * MAP19: The Spiral
 * MAP20: Breakdown
 * MAP21: Pitfalls
 * MAP22: Burnt Offerings
 * MAP23: Unholy Temple
 * MAP24: No Escape
 * MAP28: The Absolution
 * MAP25: Cat And Mouse
 * MAP26: Hardcore
 * MAP27: Playground

Monsters
Doom 64 includes the following monsters from Doom and Doom II: Doom 64 also has new monsters, which are: Doom 64 had monsters that didn't make it to the final cut:
 * Arachnotron (Doom 64)
 * Baron of Hell (Doom 64)
 * Cacodemon (Doom 64)
 * Cyberdemon (Doom 64)
 * Demon (Doom 64)
 * Hell Knight (Doom 64)
 * Imp (Doom 64)
 * Lost Soul (Doom 64)
 * Mancubus (Doom 64)
 * Pain elemental (Doom 64)
 * Shotgun Guy (Doom 64)
 * Spectre (Doom 64)
 * Zombieman (Doom 64)
 * Mother Demon
 * Nightmare Imp
 * Hellhound (Doom 64)
 * Unnamed Female Monster

Source ports
The following source ports are capable of running Doom 64:

Doom 64: Absolution TC for Doomsday
Since the release of the Doom source code for the computer games, programmers have created feature-enhanced versions of the computer Doom game in their own source ports. Several fans of Doom 64 decided to work to convert the game's exclusive content to the computer using Doomsday engine. This stand alone mod, built on the 1.7.14 release of Doomsday, titled Doom 64: Absolution, was released in 2003. It included near-identical, albeit limited representations of the original Doom 64 levels game along with some new maps of its own. It appealed to many fans as a way to play through the game on a computer without using emulation. However, one of its authors, Samuel "Kaiser" Villarreal, not being pleased with the feel of the game, started working on a more faithful representation of the console game, which later led the TC to be succeeded by Doom 64 EX.

Doom 64: Retribution for GZDoom
In December of 2016, it was announced on the ZDoom forums that Doom 64 was being modded to work with OpenGL-capable source port GZDoom. Upon its version 1.0 release on March 31, 2017, it included two options after choosing "New game" -- Doom 64, which let you play through all of the original Doom 64 levels; and Bonus Fun Maps. Selecting Bonus Fun Maps would take you to a hub where you can choose to play a few of the secret levels in Doom 64 -- Cat and Mouse, Hardcore, and Playground. Two new maps are accessible through the Bonus Fun Maps hub: TitleMap (which was the very map used for Doom 64's opening animation) and Test Facility (which allows the player to view different rooms to test certain items and effects, such as fog, lighting, props, and enemy interaction through a monster-versus-monster arena). Another new feature was the addition of "modern" weapon animations, which are reminiscent of weapon animations from Doom and Doom II. The port is available as its own IWAD but requires an external file for music. Another bonus episode planned for a future update is titled "Retribution".