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 launch for the Sony PlayStation 4, Nintendo Switch, Microsoft Xbox One, the app store for, and Apple's iOS app store.

Ultimate Doom and Doom II

 * Local multiplayer is available.
 * Cheat codes are 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. Instead, the symbol is replaced by a red and white pill.
 * A new DMENUPIC lump is used. This was the title screen in the original Xbox 360 version.
 * The engine ignores the sound effects' sample rate, and instead uses a fixed rate of 11025 Hz. The "item respawn" sound (DSITMBK) and some super shotgun sounds (DSDBOPN, DSDBCLS, DSDBLOAD), however, are still sampled at 22050 Hz; therefore when they are played back they are slower and lower pitched than intended.
 * The player's view bobbing is reduced by 25%.
 * Unlike the Gravis UltraSound Classic patch set v4.11 used by the BFG Edition, the music originally played at a noticeable reduced rate and wrong sound samples. This was later rectified with the update where the music played now closely resembles if not similar to the Roland SC-55 sound font.

Ultimate Doom specific

 * All animation has been removed from the intermission screens; the lumps for the animations are still present in the IWAD though.

Doom II specific
Several of the changes made to Doom II may cause compatibility issues with classic source ports:
 * All Wolfenstein SS have been search-and-replaced by zombiemen.
 * No Rest For The Living is excised from tnis port. In its place is the inclusion of The Master Levels.

Trivia
Doom and Doom II originally shipped with much criticized Bethesda.net login screen upon startup (for the purposes of rewards via Slayer's Club), which in a later update made them less intrusive.