Final Doom (or Final DOOM as a brand) is a pair of standalone Doom II modifications, TNT: Evilution and The Plutonia Experiment, which include full sets of new levels, some new graphics and textures and some new music in the former case, in addition to most of the resources from Doom and Doom II. It was published on June 17, 1996 by id Software under the initiative of John Romero and developed by members of the fan community belonging to TeamTNT.
TNT: Evilution was developed independently by TeamTNT, and was purchased by id Software when it was practically complete. The Plutonia Experiment, on the other hand, was completed specifically for Final Doom after its authors showed some of the id Software developers an incomplete set of levels. Its two authors, while part of TeamTNT and also contributors to Evilution, produced Plutonia independently. The Plutonia Experiment is significantly harder than TNT: Evilution.
Each of the two standalone IWADs is presented as a sequel to Doom II, referencing events from the original game in their background stories, particularly the invasion of Earth, but without referencing each other in any way. Contrary to what many believe, Final Doom does not require the original Doom II in order to be played; although it is possible to use Final Doom IWADs as PWADs with Doom II.
Since the Final Doom IWADs each contain most of the resources from Doom II, and replace the rest, they can be used along with add-ons made for Doom II, notwithstanding some possible visual inconsistencies of minor importance.
It is not clear who made the modifications to the engine. It uses the sources from The Ultimate Doom, being identical to the engine from the expansion of Doom in most respects (and is likewise marked as v1.9 regardless of differences). It is even capable of running Thy Flesh Consumed if used with the corresponding IWAD, but also detects the new Final Doom IWADs and adds the necessary text strings for the intermission screens and level names when needed (and without losing the data needed to run Doom II). If a user places various IWADs in a single directory the engine selects the new IWADs before Doom II or Doom, and Plutonia before Evilution.
Since it is derived from the source used for The Ultimate Doom, it may also display incompatible lost soul behavior when playing demos recorded with Doom version 1.9. There is, however, one additional minor difference that may also affect compatibility, a bug in the teleportation behavior where the altitude of a teleporting thing is not checked.
 Technical trivia
- When using Final Doom's engine, setting joyb_speed to 31 in the configuration file does not make the player always run as in version 1.9, though the value of 29 works in all versions.
 PlayStation version
Final Doom was ported to the PlayStation game console. It includes levels from The Master Levels, TNT, and Plutonia, in that order. However, out of this pool of eighty-five levels, only thirty are included (the back of the package states "over thirty" levels). While The Master Levels (13 out of 21 levels included) and TNT (11 out of 32 levels included) are reasonably well represented, only 6 out of 32 Plutonia levels made the cut. It carries over the features from Doom on the PlayStation, which include new sounds, ambient music, colored lighting and animated fire skies; also, it adds support for the PlayStation Mouse. Given that many of the Final Doom levels are more complex than those of previous Doom games, there is a greater chance of the player encountering slowdown. The spiderdemon enemy, though in the cast call at the end, does not appear in the game. Like the original Doom release for the PlayStation, passwords are used instead of save files. The super shotgun possesses different graphics in all versions of this port except the Japanese one.
 Legal issues in Germany
The game was put on the Index of the Bundesprüfstelle für jugendgefährdende Schriften (Medien) on 30 April 1997 (date of official announcement). This meant that the game could not be advertised, sold, rented, or otherwise given to minors. The restrictions on Doom were lifted on 31 August 2011 after an appeal from id Software's parent company, ZeniMax Media.