Doom Classic Unity port

The Doom Classic Unity port is a series of official ports of Doom and Doom II initially developed by Nerve Software in cooperation with id Software and first published by Bethesda on as part of the "Year of Doom" promotional campaign. It was initially announced on stage during the QuakeCon 2019 (DoomCon) keynote presentation. The port is based on the Doom Classic codebase, but replaces the id Tech 4 shell with one based on the game engine. This offers immediate portability to a wide array of targets - the Doom and Doom II ports were available at initial launch for the Sony PlayStation 4, Nintendo Switch, Microsoft Xbox One, the app store for, and Apple's iOS app store. As of the January 9, 2020 patch, support for PC has also been added, via the Bethesda.net distribution platform.

Differences in Doom and Doom II
Note that many changes below are carried over from previous Doom Classic revisions.

Ultimate Doom and Doom II

 * Local multiplayer is available.
 * Cheat codes are only available and accessible via the Options menu.
 * There is no confirmation when selecting Nightmare! skill.
 * On Nightmare!, the fast monsters mechanic has been removed entirely: fireballs shot by imps, cacodemons, barons of Hell and Hell knights are no longer sped up, and neither is the running speed of demons. Monsters retain increased reaction times.
 * The pickup sprites for the stimpack, medikit, and berserk (STIMA0, MEDIA0, PSTRA0) are modified in compliance with the Red Cross' wish that its symbol not be used in games. Initially the pill graphics from previous Doom Classic versions were reused. This was later changed in the January 9, 2020 update (see below).
 * The DMENUPIC that was the title screen in the original Xbox 360 version is used here.
 * New to the port is the addition of creative credits that resemble the ending credit sequence of Doom (2016), where various levels and battles are shown briefly while the camera pans around and showing the names of Nerve Software key staff. Doom and Doom II each have their own sequences, and after the montage ends, the staff credits roll will begin.
 * Music tracks doesn't loop seamlessly due to the nature of them being a recording.
 * Sounds with a 22050 Hz sample rate were played incorrectly at 11025 Hz. This initially affected all sound effects as in previous Doom Classic versions. As of the January 9, 2020 update, it is partially fixed (see below).

Significant changes and additions were made in the update released on January 9, 2020:
 * Renderer framerate increased to 60 Hz, with an interpolation system written by Alex Mayfield (AlexMax).
 * An add-on system was integrated. The initial batch of supported add-ons were SIGIL, No Rest for the Living, TNT: Evilution, and The Plutonia Experiment. The Android and PC versions support addition of custom add-ons by the end user.
 * Medikits, stimpacks, and berserk packs were changed to use a green cross instead of a pill.
 * Sound effects with a 22050 Hz sample rate now play back correctly in the base games. However, they may still play back incorrectly when an add-on is loaded. This is mostly noticeable when using the super shotgun in No Rest for the Living in Doom II. The Final Doom add-ons do not exhibit this issue since they contain their own copies of these sound effects at an 11025 Hz sample rate.
 * Support for aspect ratio correction was added.
 * Support for quick save and load were added.
 * A level select menu was added, allowing the game to be started on any level at any skill.
 * A weapon carousel was added, allowing instant selection of weapons without cycling through every intermediate weapon and waiting on the resulting raise and lower animations.
 * Quick weapon swap via the directional pad was added, with the following control assignments:
 * Up: Super shotgun and shotgun
 * Right: Chaingun
 * Down: Rocket launcher
 * Left: Plasma rifle
 * Overall brightness and level brightness controls were added.
 * Random sound effect pitch can now be toggled on or off.
 * The split screen HUD for multiplayer was minimized, removing the status bar to allow more game display space.

Ultimate Doom specific

 * All animation from the intermission screens has been restored; they were originally missing from the BFG Edition.
 * The logo on E4M1: Hell Beneath has been removed, presumably to avoid trademark infringement.

Doom II specific

 * BFG Edition's MAP31: IDKFA and MAP32: Keen has been reverted back to MAP31: Wolfenstein and MAP32: Grosse alongside their respective map music, D_EVIL and D_ULTIMA.
 * The ZWOLF* texture with Nazi iconography (Hitler portraits, swastikas, Reichsadlers, etc.) have been censored. These were initially identical to the versions that appeared in BFG Edition, but have been edited in the January 9, 2020 patch to be closer to the original textures. The BFG Edition versions of textures which had Nazi detailing were the same as undetailed versions of those wall textures. As of the patch, they have instead been restored to the original versions and then edited, replacing swastikas with the triangle logo used in the German version of , while Hitler has lost his toothbrush mustache, making him resemble the Staatmeister from the Super Nintendo version of Wolfenstein 3D. The definitions in TEXTURE1 are identical; it is the patches that have been changed.
 * The Wolfenstein SS (which were effectively removed in BFG Edition) have been restored. As of the January 9 patch, the second half of their sight sound has been redubbed - they now say "schutzkämpfer" instead of "schutzstaffel", the first half still using John Romero's voice while the other half was re-recorded by Mike Rubits of id Software. Their death sounds are as normal.
 * MAP06: The Crusher has been edited to remove the linedef actions on the door track of the red key door which would crash the game.

Trivia

 * Doom and Doom II originally shipped with a much criticized Bethesda.net login screen upon startup (for the purposes of rewards via the Slayers Club), which was made less intrusive in a later update.
 * The music originally played recordings of a original songs at a noticeable reduced rate and wrong sound samples. This was later rectified with the update which uses recordings of the music played through a . Later, the  update brought back direct MUS and MIDI playback, but only for addons.